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Astrology & Astronomy

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Astrology 1Astronomy 18

ReferencesArticle Sources and Contributors 34Image Sources, Licenses and Contributors 36

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Astrology 1

AstrologyNot to be confused with Astronomy, the scientific study of celestial objects.

Astrology

The astrological signs

•• Aries•• Taurus•• Gemini•• Cancer•• Leo•• Virgo•• Libra•• Scorpio•• Sagittarius•• Capricorn•• Aquarius•• Pisces

Astrology categories

Expand listfor reference

Branches of astrology•• Chinese•• Decumbiture•• Electional•• Financial•• Hellenistic•• Horary•• Locational•• Psychological•• Meteorological•• Hindu

The planets in astrology

•• Sun•• Moon•• Mercury

Astrology 2

•• Venus•• Mars•• Ceres•• Jupiter•• Saturn•• Uranus•• Neptune•• Pluto

Astrologyportal

Astrologyproject

•• Astrologers•• Astrological organizations•• Astrology and science

•• v•• t• e [1]

Astrology, or astromancy, consists of several systems of divination based on the premise that there is a relationshipbetween astronomical phenomena and events in the human world. Many cultures have attached importance toastronomical events, and the Indians, Chinese, and Mayans developed elaborate systems for predicting terrestrialevents from celestial observations. In the West, astrology most often consists of a system of horoscopes purporting toexplain aspects of a person's personality and predict future events in their life based on the positions of the sun,moon, and other celestial objects at the time of their birth. The majority of professional astrologers rely on suchsystems.:83

Throughout most of its history, astrology was considered a scholarly tradition. It was accepted in political andacademic contexts, and was connected with other studies, such as astronomy, alchemy, meteorology, and medicine.At the end of the 17th century, new scientific concepts in astronomy and physics (such as heliocentrism andNewtonian mechanics) called astrology into question. Astrology thus lost its academic and theoretical standing, andcommon belief in astrology has largely declined. Astrology has been rejected by the scientific community as apseudoscience, having no validity or explanatory power for describing the universe. Among other issues, there is noproposed mechanism of action by which the positions and motions of stars and planets could affect people andevents on Earth that does not contradict well understood basic aspects of biology and physics.:249 Scientific testing ofastrology has found no evidence to support any of the premises or purported effects outlined in astrologicaltraditions. In one study, participating astrologers attempting to match natal charts with profiles generated by apsychological inventory produced results not significantly at variance with random chance.:424

Astrology has been dated to at least the 2nd millennium BCE, with roots in calendrical systems used to predictseasonal shifts and to interpret celestial cycles as signs of divine communications. A form of astrology was practisedin the first dynasty of Mesopotamia (1950–1651 BCE). Chinese astrology was elaborated in the Zhou dynasty(1046–256 BCE). Hellenistic astrology after 332 BCE mixed Babylonian astrology with Egyptian Decanic astrologyin Alexandria, creating horoscopic astrology. Alexander the Great's conquest of Asia allowed astrology to spread toAncient Greece and Rome. In Rome, astrology was associated with "Chaldean wisdom". After the conquest ofAlexandria in the 7th century, astrology was taken up by Islamic scholars, and Hellenistic texts were translated intoArabic and Persian. In the 12th century, Arabic texts were imported to Europe and translated into Latin, helping toinitiate the European Renaissance, when major astronomers including Tycho Brahe, Johannes Kepler and Galileopractised as court astrologers. Astrological references appear in literature in the works of poets such as DanteAlighieri and Geoffrey Chaucer, and of playwrights such as Christopher Marlowe and William Shakespeare.

Astrology 3

Etymology

Marcantonio Raimondi engraving,15th century

The word astrology comes from the early Latin word astrologia, deriving fromthe Greek noun ἀστρολογία, 'account of the stars'. Astrologia later passed intomeaning 'star-divination' with astronomia used for the scientific term.

History

Main article: History of astrologyMany cultures have attached importance to astronomical events, and the Indians,Chinese, and Mayans developed elaborate systems for predicting terrestrialevents from celestial observations. In the West, astrology most often consists of asystem of horoscopes purporting to explain aspects of a person's personality andpredict future events in their life based on the positions of the sun, moon, andother celestial objects at the time of their birth. The majority of professionalastrologers rely on such systems.:83

Astrology has been dated to at least the 2nd millennium BCE, with roots incalendrical systems used to predict seasonal shifts and to interpret celestial cycles as signs of divine communications.A form of astrology was practised in the first dynasty of Mesopotamia (1950–1651 BCE). Chinese astrology waselaborated in the Zhou dynasty (1046–256 BCE). Hellenistic astrology after 332 BCE mixed Babylonian astrologywith Egyptian Decanic astrology in Alexandria, creating horoscopic astrology. Alexander the Great's conquest ofAsia allowed astrology to spread to Ancient Greece and Rome. In Rome, astrology was associated with 'Chaldeanwisdom'. After the conquest of Alexandria in the 7th century, astrology was taken up by Islamic scholars, andHellenistic texts were translated into Arabic and Persian. In the 12th century, Arabic texts were imported to Europeand translated into Latin, helping to initiate the European Renaissance, when major astronomers including TychoBrahe, Johannes Kepler and Galileo practised as court astrologers. Astrological references appear in literature in theworks of poets such as Dante Alighieri and Geoffrey Chaucer, and of playwrights such as Christopher Marlowe andWilliam Shakespeare.

Throughout most of its history, astrology was considered a scholarly tradition. It was accepted in political andacademic contexts, and was connected with other studies, such as astronomy, alchemy, meteorology, and medicine.At the end of the 17th century, new scientific concepts in astronomy and physics (such as heliocentrism andNewtonian mechanics) called astrology into question. Astrology thus lost its academic and theoretical standing, andcommon belief in astrology has largely declined.

Ancient worldFor more details on ancient astrology, see Babylonian astrology.Astrology, in its broadest sense, is the search for meaning in the sky.:2,3 Early evidence for humans makingconscious attempts to measure, record, and predict seasonal changes by reference to astronomical cycles, appears asmarkings on bones and cave walls, which show that lunar cycles were being noted as early as 25,000 years ago.:81ff

This was a first step towards recording the Moon's influence upon tides and rivers, and towards organizing acommunal calendar. Agricultural needs were addressed with increasing knowledge of constellations which appear inthe different seasons, allowing the rising of particular star-groups to herald annual floods or seasonal activities. Bythe 3rd millennium BCE, civilizations had sophisticated awareness of celestial cycles, and may have orientedtemples in alignment with heliacal risings of the stars.There is scattered evidence to suggest that the oldest known astrological references are copies of texts made in the ancient world. The Venus tablet of Ammisaduqa (compiled in Babylon around 1700 BCE) is reported to have been

Astrology 4

made during the reign of king Sargon of Akkad (2334–2279 BCE).[2] A scroll documenting an early use of electionalastrology is doubtfully ascribed to the reign of the Sumerian ruler Gudea of Lagash (c. 2144 – 2124 BCE). Thisdescribes how the gods revealed to him in a dream the constellations that would be most favourable for the plannedconstruction of a temple.[3] However, there is controversy about whether these were genuinely recorded at the timeor merely ascribed to ancient rulers by posterity. The oldest undisputed evidence of the use of astrology as anintegrated system of knowledge is therefore attributed to the records of the first dynasty of Mesopotamia(1950–1651 BCE). This astrology had some parallels with Hellenistic Greek (western) astrology, including thezodiac, a norming point near 9 degrees in Aries, the trine aspect, planetary exaltations, and the dodekatemoria (thetwelve divisions of 30 degrees each). However, the Babylonians viewed celestial events as possible signs rather thanas causes of physical events.The system of Chinese astrology was elaborated during the Zhou dynasty (1046–256 BCE) and flourished during theHan Dynasty (2nd century BCE to 2nd century CE), during which all the familiar elements of traditional Chineseculture – the Yin-Yang philosophy, theory of the five elements, Heaven and Earth, Confucian morality – werebrought together to formalise the philosophical principles of Chinese medicine and divination, astrology andalchemy.:3,4

Ancient objections

The Roman orator Cicero objected toastrology.

Cicero stated the twins objection (that with close birth times, personal outcomescan be very different), later developed by Saint Augustine.[4] He argued thatsince the other planets are much more distant from the earth than the moon, theycould have only very tiny influence compared to the moon's.[5] He also arguedthat if astrology explains everything about a person's fate, then it wrongly ignoresthe visible effect of inherited ability and parenting, changes in health worked bymedicine, or the effects of the weather on people.[6]

Plotinus argued that since the fixed stars are much more distant than the planets,it is laughable to imagine the planets' effect on mankind should depend on theirposition with respect to the zodiac. He also argues that the interpretation of themoon's conjunction with a planet as good when the moon is full, but bad whenthe moon is waning, is clearly wrong, as from the moon's point of view, half ofher surface is always in sunlight; and from the planet's point of view, waningshould be better, as then the planet sees some light from the moon, but when themoon is full to us, it is dark, and therefore bad, on the side facing the planet.[7]

Favorinus argued that it was absurd to imagine that stars and planets would affect human bodies in the same way asthey affect the tides,[8] and equally absurd that small motions in the heavens cause large changes in people's fates.Sextus Empiricus argued that it was absurd to link human attributes with myths about the signs of the zodiac.[9]

Carneades argued that belief in fate denies free will and morality; that people born at different times can all die in thesame accident or battle; and that contrary to uniform influences from the stars, tribes and cultures are all different.

Astrology 5

Hellenistic EgyptMain article: Hellenistic astrology

1484 copy of first page of Ptolemy'sTetrabiblos, translated into Latin by

Plato of Tivoli

In 525 BCE, Egypt was conquered by the Persians. The 1st century BCEEgyptian Dendera Zodiac shares two signs – the Balance and the Scorpion –with Mesopotamian astrology.[10]

With the occupation by Alexander the Great in 332 BCE, Egypt becameHellenistic. The city of Alexandria was founded by Alexander after the conquest,becoming the place where Babylonian astrology was mixed with EgyptianDecanic astrology to create Horoscopic astrology. This contained the Babylonianzodiac with its system of planetary exaltations, the triplicities of the signs and theimportance of eclipses. It used the Egyptian concept of dividing the zodiac intothirty-six decans of ten degrees each, with an emphasis on the rising decan, andthe Greek system of planetary Gods, sign rulership and four elements.[11] 2ndcentury BCE texts predict positions of planets in zodiac signs at the time of therising of certain decans, particularly Sothis.[12] The astrologer and astronomerPtolemy lived in Alexandria. Ptolemy's work the Tetrabiblos formed the basis ofWestern astrology, and "enjoyed almost the authority of a Bible among the astrological writers of a thousand years ormore".[13]

Greece and RomeThe conquest of Asia by Alexander the Great exposed the Greeks to ideas from Syria, Babylon, Persia and centralAsia.[14] Around 280 BCE, Berossus, a priest of Bel from Babylon, moved to the Greek island of Kos, teachingastrology and Babylonian culture.[15] By the 1st century BCE, there were two varieties of astrology, one usinghoroscopes to describe the past, present and future; the other, theurgic, emphasising the soul's ascent to the stars.[16]

Greek influence played a crucial role in the transmission of astrological theory to Rome.[17]

The first definite reference to astrology in Rome comes from the orator Cato, who in 160 BCE warned farmoverseers against consulting with Chaldeans,[18] who were described as Babylonian 'star-gazers'.[19] Among bothGreeks and Romans, Babylonia (also known as Chaldea) became so identified with astrology that 'Chaldean wisdom'became synonymous with divination using planets and stars.[20] The 2nd-century Roman poet and satirist Juvenalcomplains about the pervasive influence of Chaldeans, saying "Still more trusted are the Chaldaeans; every worduttered by the astrologer they will believe has come from Hammon's fountain".[21]

One of the first astrologers to bring Hermetic astrology to Rome was Thrasyllus, astrologer to the emperor Tiberius,the first emperor to have had a court astrologer,[22] though his predecessor Augustus had used astrology to helplegitimise his Imperial rights.[23]

Astrology 6

Mediæval world

Islamic

Main article: Astrology in medieval Islam

Latin translation of Abū Maʿshar's De MagnisConiunctionibus ('Of the great conjunctions'),

Venice, 1515.

Astrology was taken up by Islamic scholars following the collapse ofAlexandria to the Arabs in the 7th century, and the founding of theAbbasid empire in the 8th. The second Abbasid caliph, Al Mansur(754–775) founded the city of Baghdad to act as a centre of learning,and included in its design a library-translation centre known as Baytal-Hikma 'House of Wisdom', which continued to receive developmentfrom his heirs and was to provide a major impetus for Arabic-Persiantranslations of Hellenistic astrological texts. The early translatorsincluded Mashallah, who helped to elect the time for the foundation ofBaghdad, and Sahl ibn Bishr, (a.k.a. Zael), whose texts were directlyinfluential upon later European astrologers such as Guido Bonatti inthe 13th century, and William Lilly in the 17th century. Knowledge ofArabic texts started to become imported into Europe during the Latin translations of the 12th century, the effect ofwhich was to help initiate the European Renaissance.

Europe

Dante Alighieri meets the EmperorJustinian in the Sphere of Mercury,

in Canto 5 of the Paradiso.

The first astrological book published in Europe was the Liber Planetis et MundiClimatibus ("Book of the Planets and Regions of the World") which appearedbetween 1010 and 1027 AD, and may have been authored by Gerbert ofAurillac.[24] Ptolemy's second century AD Tetrabiblos was translated into Latinby Plato of Tivoli in 1138. The Dominican theologian Thomas Aquinas followedAristotle in proposing that the stars ruled the imperfect 'sublunary' body, whileattempting to reconcile astrology with Christianity by stating that God ruled thesoul.[25] The thirteenth century mathematician Campanus of Novara is said tohave devised a system of astrological houses which divides the prime verticalinto 'houses' of equal 30° arcs,[26] though the system was used earlier in the East.The thirteenth century astronomer Guido Bonatti wrote a textbook, the LiberAstronomicus, a copy of which was owned at the end of the fifteenth century byking Henry VII of England.

In Paradiso, the final part of the Divine Comedy, the Italian poet Dante Alighierireferred "in countless details" to the astrological planets, though he adaptedtraditional astrology to suit his Christian viewpoint, for example using astrological thinking in his prophecies of thereform of Christendom.

Astrology 7

Mediæval objections

The medieval theologian Isidore ofSeville criticized the predictive part

of astrology.

In the seventh century, Isidore of Seville argued in his Etymologiae thatastronomy described the movements of the heavens, while astrology had twoparts: one was scientific, describing the movements of the sun, the moon and thestars, while the other, making predictions, was theologically erroneous.[27] Incontrast, John Gower in the fourteenth century defined astrology as essentiallylimited to the making of predictions. The influence of the stars was in turndivided into natural astrology, with for example effects on tides and the growthof plants, and judicial astrology, with supposedly predictable effects onpeople.[28] The fourteenth century skeptic Nicole Oresme however includedastronomy as a part of astrology in his Livre de divinacions.[29] Oresme arguedthat current approaches to prediction of events such as plagues, wars, andweather were inappropriate, but that such prediction was a valid field of inquiry.However, he attacked the use of astrology to choose the timing of actions(so-called interrogation and election) as wholly false, and rejected the

determination of human action by the stars on grounds of free will. The friar Laurens Pignon (c. 1368–1449)similarly rejected all forms of divination and determinism, including by the stars, in his 1411 Contre lesDevineurs.[30] This was in opposition to the tradition carried by the Arab astronomer Albumasar (787-886) whoseIntroductorium in Astronomiam and De Magnis Coniunctionibus argued the view that both individual actions andlarger scale history are determined by the stars.[31]

Renaissance and Early Modern

'An Astrologer Casting a Horoscope' from RobertFludd's Utriusque Cosmi Historia, 1617

Renaissance scholars often practised astrology to pay for their researchinto other subjects.[32] Gerolamo Cardano cast the horoscope of kingEdward VI of England, while John Dee was the personal astrologer toqueen Elizabeth I of England. Catherine de Medici paid MichaelNostradamus in 1566 to verify the prediction of the death of herhusband, king Henry II of France made by her astrologer LucusGauricus. Major astronomers who practised as court astrologersincluded Tycho Brahe in the royal court of Denmark, Johannes Keplerto the Habsburgs and Galileo Galilei to the Medici. The astronomerand spiritual astrologer Giordano Bruno was burnt at the stake forheresy in Rome in 1600.

Ephemerides with complex astrological calculations, and almanacsinterpreting celestial events for use in medicine and for choosing timesto plant crops, were popular in Elizabethan England. In 1597, the English mathematician and physician ThomasHood made a set of paper instruments using revolving overlays which enabled students to work out relationshipsbetween the fixed stars or constellations, the midheaven, and the twelve astrological houses. Hood's instruments alsoillustrated for pedagogical purposes the supposed relationships between the signs of the zodiac, the planets, and theparts of the human body which were believed to be governed by the planets and signs. While Hood's presentationwas innovative, his astrological information was largely standard and was taken from Gerard Mercator's astrologicaldisc made in 1551, or a source used by Mercator.

English astrology had reached its zenith by the 17th century.[33] Astrologers were theorists, researchers, and social engineers, as well as providing individual advice to everyone from monarchs downwards. Among other things, astrologers could advise on the best time to take a journey or harvest a crop, diagnose and prescribe for physical or

Astrology 8

mental illnesses, and predict natural disasters. This underpinned a system in which everything - people, the world,the universe - was understood to be interconnected, and astrology co-existed happily with religion, magic andscience.[34]

Enlightenment period and onwardsDuring The Enlightenment, intellectual sympathy for astrology fell away, leaving only a popular followingsupported by cheap almanacs. One English almanac compiler, Richard Saunders, followed the spirit of the age byprinting a derisive Discourse on the Invalidity of Astrology, while in France Pierre Bayle's Dictionnaire of 1697stated that the subject was puerile. The Anglo-Irish satirist Jonathan Swift ridiculed the Whig political astrologerJohn Partridge.Astrology saw a popular revival starting in the 19th century as part of a general revival of spiritualism and later NewAge philosophy,:239–249 and through the influence of mass media such as newspaper horoscopes.:259–263 Early in the20th century the psychiatrist Carl Jung developed some concepts concerning astrology, which led to the developmentof psychological astrology.:251–256[35][36]

Principles and practiceAdvocates have defined astrology as a symbolic language, an art form, a science, and a method of divination.[37][38]

Although most cultural systems of astrology share common roots in ancient philosophies that influenced each other,many have unique methodologies which differ from those developed in the West. These include Hindu astrology(also known as "Indian astrology" and in modern times referred to as "Vedic astrology") and Chinese astrology, bothof which have influenced the world's cultural history.

WesternFor more details on this topic, see Western astrology.Western astrology is a form of divination based on the construction of a horoscope for an exact moment, such as aperson's birth. It uses the tropical zodiac, which is aligned to the equinoctial points.[39]

Western astrology is founded on the movements and relative positions of celestial bodies such as the Sun, Moon andplanets, which are analyzed by their movement through signs of the zodiac (twelve spatial divisions of the ecliptic)and by their aspects (based on geometric angles) relative to one another. They are also considered by their placementin houses (twelve spatial divisions of the sky). Astrology's modern representation in western popular media is usuallyreduced to sun sign astrology, which considers only the zodiac sign of the Sun at an individual's date of birth, andrepresents only 1/12 of the total chart.The horoscope visually expresses the set of relationships for the time and place of the chosen event. Theserelationships are between the seven 'planets', signifying tendencies such as war and love; the twelve signs of thezodiac; and the twelve houses. Each planet is in a particular sign and a particular house at the chosen time, whenobserved from the chosen place, creating two kinds of relationship. A third kind is the aspect of each planet to everyother planet, where for example two planets 120° apart (in 'trine') are in a harmonious relationship, but two planets90° apart ('square') are in a conflicted relationship. Together these relationships and their interpretations supposedlyform "the language of the heavens speaking to learned men".Along with tarot divination, astrology is one of the core studies of Western esotericism, and as such has influencedsystems of magical belief not only among Western esotericists and Hermeticists, but also belief systems such asWicca that have borrowed from or been influenced by the Western esoteric tradition. Tanya Luhrmann has said that"all magicians know something about astrology," and refers to a table of correspondences in Starhawk's The SpiralDance, organized by planet, as an example of the astrological lore studied by magicians.

Astrology 9

Hindu

Page from an Indian astrologicaltreatise, c. 1750

For more details on this topic, see Hindu astrology.Hindu natal astrology originated with western (Hellenistic) astrology in ancienttimes,:361 though incorporating the Hindu lunar mansions. The names of thesigns (e.g. Greek 'Kpios' for Aries, Hindi 'Kriya'), the planets (e.g. Greek 'Helios'for Sun, astrological Hindi 'Heli'), and astrological terms (e.g. Greek 'apoklima'and 'sunaphe' for declination and planetary conjunction, Hindi 'apoklima' and'sunapha' respectively) in Varaha Mihira's texts are considered conclusiveevidence of a Greek origin for Hindu astrology. The Indian techniques may alsohave been augmented with some of the Babylonian techniques.:231

Chinese and East-Asian

For more details on this topic, see Chinese astrology and Chinese zodiac.Chinese astrology has a close relation with Chinese philosophy (theory of thethree harmonies: heaven, earth and man) and uses concepts such as yin and yang,the Five phases, the 10 Celestial stems, the 12 Earthly Branches, and shichen (時辰 a form of timekeeping used for religious purposes). The early use of Chinese astrology was mainly confined topolitical astrology, the observation of unusual phenomena, identification of portents and the selection of auspiciousdays for events and decisions.:22,85,176

The constellations of the Zodiac of western Asia and Europe were not used; instead the sky is divided into ThreeEnclosures (三 垣 sān yuán), and Twenty-eight Mansions (二 十 八 宿 èrshíbā xiù) in twelve Ci (十 二 次).[40]

The Chinese zodiac of twelve animal signs is said to represent twelve different types of personality. It is based oncycles of years, lunar months, and two-hour periods of the day (the shichen). The zodiac traditionally begins with thesign of the Rat, and the cycle proceeds through 11 other animals signs: the Ox, Tiger, Rabbit, Dragon, Snake, Horse,Goat, Monkey, Rooster, Dog and Pig.[41] Complex systems of predicting fate and destiny based on one's birthday,birth season, and birth hours, such as ziping and Zi Wei Dou Shu (simplified Chinese: 紫 微 斗 数; traditionalChinese: 紫 微 斗 數; pinyin: zǐwēidǒushù) are still used regularly in modern day Chinese astrology. They do notrely on direct observations of the stars.The Korean zodiac is identical to the Chinese one. The Vietnamese zodiac is almost identical to Chinese zodiacexcept the second animal is the Water Buffalo instead of the Ox, and the fourth animal is the Cat instead of theRabbit. The Japanese have since 1873 celebrated the beginning of the new year on 1 January as per the GregorianCalendar. The Thai zodiac begins, not at Chinese New Year, but either on the first day of fifth month in the Thailunar calendar, or during the Songkran festival (now celebrated every 13–15 April), depending on the purpose of theuse.[42]

Theological viewpointsSee also: Christianity and astrology, Jewish views on astrology and Muslim views on astrology

AncientSt. Augustine (354-430) believed that the determinism of astrology conflicted with the Christian doctrines of man'sfree will and responsibility, and God not being the cause of evil, but he also grounded his opposition philosophically,citing the failure of astrology to explain twins who behave differently although conceived at the same moment andborn at approximately the same time.

Astrology 10

MediævalSome of the practices of astrology were contested on theological grounds by medieval Muslim astronomers such asAl-Farabi (Alpharabius), Ibn al-Haytham (Alhazen) and Avicenna. They said that the methods of astrologersconflicted with orthodox religious views of Islamic scholars, by suggesting that the Will of God can be known andpredicted in advance. For example, Avicenna's 'Refutation against astrology', Risāla fī ibṭāl aḥkām al-nojūm, arguesagainst the practice of astrology while supporting the principle that planets may act as agents of divine causation.Avicenna considered that the movement of the planets influenced life on earth in a deterministic way, but arguedagainst the possibility of determining the exact influence of the stars.[43] Essentially, Avicenna did not deny the coredogma of astrology, but denied our ability to understand it to the extent that precise and fatalistic predictions couldbe made from it.[44] Ibn Qayyim Al-Jawziyya (1292–1350), in his Miftah Dar al-SaCadah, also used physicalarguments in astronomy to question the practice of judicial astrology. He recognized that the stars are much largerthan the planets, and argued:

And if you astrologers answer that it is precisely because of this distance and smallness that their influencesare negligible, then why is it that you claim a great influence for the smallest heavenly body, Mercury? Why isit that you have given an influence to al-Ra's and al-Dhanab, which are two imaginary points [ascending anddescending nodes]?—Ibn Qayyim Al-Jawziyya

ModernDivination, including predictive astrology, is stated in the Catechism of the Catholic Church to be incompatible withmodern Catholic beliefs such as free will:

All forms of divination are to be rejected: recourse to Satan or demons, conjuring up the dead or otherpractices falsely supposed to "unveil" the future. Consulting horoscopes, astrology, palm reading,interpretation of omens and lots, the phenomena of clairvoyance, and recourse to mediums all conceal a desirefor power over time, history, and, in the last analysis, other human beings, as well as a wish to conciliatehidden powers. They contradict the honor, respect, and loving fear that we owe to God alone.—Catechism of the Catholic Church

Astrology 11

Scientific analysis and criticismMain article: Astrology and science

Popper proposed falsifiability as thatwhich distinguishes science from

non-science, using astrology as theexample of an idea which has not

dealt with falsification duringexperiment.

Astrology has been rejected by the scientific community as having noexplanatory power for describing the universe and is considered apseudoscience.:1350 Scientific testing of astrology has been conducted, and noevidence has been found to support any of the premises or purported effectsoutlined in astrological traditions.:424 There is no proposed mechanism of actionby which the positions and motions of stars and planets could affect people andevents on Earth that does not contradict well understood, basic aspects of biologyand physics.:249 Those who continue to have faith in astrology have beencharacterized as doing so "in spite of the fact that there is no verified scientificbasis for their beliefs, and indeed that there is strong evidence to thecontrary".[45]

It has also been shown that confirmation bias is a psychological factor thatcontributes to belief in astrology.:344:180–181:42–48 Confirmation bias is a form ofcognitive bias.[46]:553 According to available literature Astrology believers tendto selectively remember those predictions which have turned out to be true, anddo not remember those predictions which happen to be false. Another, separate,form of confirmation bias also plays a role, where believers often fail todistinguish between messages that demonstrate special ability and those which do not.:180–181 Thus there are twodistinct forms of confirmation bias that are under study with respect to astrological belief.:180–181

DemarcationUnder the criterion of falsifiability, first proposed by philosopher of science Karl Popper, astrology is apseudoscience. Popper regarded astrology as "pseudo-empirical" in that "it appeals to observation and experiment",but "nevertheless does not come up to scientific standards".[47]:44 In contrast to scientific disciplines, astrology hasnot responded to falsification through experiment.:206 In contrast to Popper, the philosopher Thomas Kuhn arguedthat it was not lack of falsifiability that makes astrology unscientific, but rather that the process and concepts ofastrology are non-empirical.:401

To Kuhn, although astrologers had, historically, made predictions that "categorically failed", this in itself does notmake it unscientific, nor do the attempts by astrologers to explain away the failure by claiming it was due to thecreation of a horoscope being very difficult. Rather, in Kuhn's eyes, astrology is not science because it was alwaysmore akin to medieval medicine; they followed a sequence of rules and guidelines for a seemingly necessary fieldwith known shortcomings, but they did no research because the fields are not amenable to research,:8 and so "theyhad no puzzles to solve and therefore no science to practise".:401:8 While an astronomer could correct for failure, anastrologer could not. An astrologer could only explain away failure but could not revise the astrological hypothesisin a meaningful way. As such, to Kuhn, even if the stars could influence the path of humans through life astrology isnot scientific.:8

Philosopher Paul Thagard believed that astrology cannot be regarded as falsified in this sense until it has been replaced with a successor. In the case of predicting behaviour, psychology is the alternative.:228 To Thagard a further criterion of demarcation of science from pseudoscience was that the state-of-the-art must progress and that the community of researchers should be attempting to compare the current theory to alternatives, and not be "selective in considering confirmations and disconfirmations".:227–228 Progress is defined here as explaining new phenomena and solving existing problems, yet astrology has failed to progress having only changed little in nearly 2000 years.:228:549

To Thagard, astrologers are acting as though engaged in Normal science believing that the foundations of astrology

Astrology 12

were well established despite the "many unsolved problems", and in the face of better alternative theories(Psychology). For these reasons Thagard viewed astrology as pseudoscience.:228

For the philosopher Edward W. James, astrology is irrational not because of the numerous problems withmechanisms and falsification due to experiments, but because an analysis of the astrological literature shows that it isinfused with fallacious logic and poor reasoning.:34

What if throughout astrological writings we meet little appreciation of coherence, blatant insensitivity toevidence, no sense of a hierarchy of reasons, slight command over the contextual force of critieria, stubbornunwillingless to pursue an argument where it leads, stark naivete concerning the effiacacy of explanation andso on? In that case, I think, we are perfectly justified in rejecting astrology as irrational. ... Astrology simplyfails to meet the multifarious demands of legitimate reasoning."—Edward W. James:34

EffectivenessAstrology has not demonstrated its effectiveness in controlled studies and has no scientific validity.:85 Where it hasmade falsifiable predictions under controlled conditions, they have been falsified.:424 One famous experimentincluded 28 astrologers who were asked to match over a hundred natal charts to psychological profiles generated bythe California Psychological Inventory (CPI) questionnaire.[48] The double-blind experimental protocol used in thisstudy was agreed upon by a group of physicists and a group of astrologers nominated by the National Council forGeocosmic Research, who advised the experimenters, helped ensure that the test was fair:117:420 and helped draw thecentral proposition of natal astrology to be tested.:419 They also chose 26 out of the 28 eight astrologers for the tests(two more volunteered afterwards).:420 The study, published in Nature in 1985, found that predictions based on natalastrology were no better than chance, and that the testing "clearly refutes the astrological hypothesis".In 1955, astrologer and psychologist Michel Gauquelin stated that although he had failed to find evidence to supportsuch indicators as the zodiacal signs and planetary aspects in astrology, he had found positive correlations betweenthe diurnal positions of some of the planets and success in some professions which astrology traditionally associateswith those planets. The best-known of Gauquelin's findings is based on the positions of Mars in the natal charts ofsuccessful athletes and became known as the "Mars effect".:213 A study conducted by seven French scientistsattempted to replicate the claim, but found no statistical evidence.:213–214 They attributed the effect to selective biason Gauquelin's part, accusing him of attempting to persuade them to add or delete names from their study.Geoffrey Dean has suggested that the effect may be caused by self-reporting of birth dates by parents rather than anyissue with the study by Gauquelin. The suggestion is that a small subset of the parents may have had changed birthtimes to be consistent with better astrological charts for a related profession. The sample group was taken from atime where belief in astrology was more common. Gauquelin had failed to find the Mars effect in more recentpopulations, where a nurse or doctor recorded the birth information. The number of births under astrologicallyundesirable conditions was also lower, indicating more evidence that parents choose dates and times to suit theirbeliefs.:116

Dean, a scientist and former astrologer, and psychologist Ivan Kelly conducted a large scale scientific test, involvingmore than one hundred cognitive, behavioural, physical and other variables, but found no support for astrology.Furthermore, a meta-analysis was conducted pooling 40 studies consisting of 700 astrologers and over 1,000 birthcharts. Ten of the tests, which had a total of 300 participating, involved the astrologers picking the correct chartinterpretation out of a number of others which were not the astrologically correct chart interpretation (usually 3 to 5others). When the date and other obvious clues were removed no significant results were found to suggest there wasany preferred chart.:190

Astrology 13

Lack of mechanisms and consistencyTesting the validity of astrology can be difficult because there is no consensus amongst astrologers as to whatastrology is or what it can predict.:83 Most professional astrologers are paid to predict the future or describe aperson's personality and life, but most horoscopes only make vague untestable statements that can apply to almostanyone.:83

Many astrologers claim that astrology is scientific, while some have proposed conventional causal agents such aselectromagnetism and gravity. Scientists reject these mechanisms as implausible since, for example, the magneticfield, when measured from earth, of a large but distant planet such as Jupiter is far smaller than that produced byordinary household appliances.Western astrology has taken the earth's axial precession (also called precession of the equinoxes) into account sincePtolemy's Almagest, so the 'first point of Aries', the start of the astrological year, continually moves against thebackground of the stars.[49] The tropical zodiac has no connection to the stars, and as long as no claims are made thatthe constellations themselves are in the associated sign, astrologers avoid the concept that precession seeminglymoves the constellations. Charpak and Broch, noting this, referred to astrology based on the tropical zodiac as being"...empty boxes that have nothing to do with anything and are devoid of any consistency or correspondence with thestars." Sole use of the tropical zodiac is inconsistent with references made, by the same astrologers, to the Age ofAquarius, which depends on when the vernal point enters the constellation of Aquarius.Astrologers usually have only a small knowledge of astronomy and they often do not take into account basic featuressuch as the precession of the equinoxes which would change the position of the sun with time; they commented onthe example of Elizabeth Teissier who claimed that "the sun ends up in the same place in the sky on the same dateeach year" as the basis for claims that two people with the same birthday but a number of years apart should be underthe same planetary influence. Charpak and Broch noted that "there is a difference of about twenty-two thousandmiles between Earth's location on any specific date in two successive years" and that thus they should not be underthe same influence according to astrology. Over a 40 years period there would be a difference greater than 780,000miles.:6–7

Cultural impact

Mars, the Bringer of War

Mars, performed by the U.S. Air Force Band

Venus, the Bringer of Peace

Venus, performed by the U.S. Air Force Band

Mercury, the Winged Messenger

Mercury, performed by the U.S. Air Force Band

Jupiter, the Bringer of Jollity

Jupiter, performed by the U.S. Air Force Band

Uranus, the Magician

Uranus, performed by the U.S. Air Force Band

Problems playing these files? See media help.

Astrology 14

Western politics and societyIn the West, political leaders have sometimes consulted astrologers. Louis de Wohl worked as an astrologer for theBritish intelligence agency MI5, after it was claimed that Adolf Hitler used astrology to time his actions. The WarOffice was "interested to know what Hitler's own astrologers would be telling him from week to week". In fact, deWohl's predictions were so inaccurate that he was soon labelled a "complete charlatan" and it was later shown thatHitler considered astrology to be "complete nonsense". After John Hinckley's attempted assassination of U.S.President Ronald Reagan, first lady Nancy Reagan commissioned astrologer Joan Quigley to act as the secret WhiteHouse astrologer. However, Quigley's role ended in 1988 when it became public through the memoirs of formerchief of staff, Donald Regan.There was a boom in interest in astrology in the late 1960s. The sociologist Marcello Truzzi described three levels ofinvolvement of "Astrology-believers" to account for its revived popularity in the face of scientific discrediting. Hefound that most astrology-believers did not claim it was a scientific explanation with predictive power. Instead, thosesuperficially involved, knowing "next to nothing" about astrology's 'mechanics', read newspaper astrology columns,and could benefit from "tension-management of anxieties" and "a cognitive belief-system that transcends science".Those at the second level usually had their horoscopes cast and sought advice and predictions. They were muchyounger than those at the first level, and could benefit from knowledge of the language of astrology and the resultingability to belong to a coherent and exclusive group. Those at the third level were highly involved and usually casthoroscopes for themselves. Astrology provided this small minority of astrology-believers with a "meaningful view oftheir universe and [gave] them an understanding of their place in it."[50] This third group took astrology seriously,possibly as a "sacred canopy", whereas the other two groups took it playfully and irreverently.In 1953, sociologist Theodor W. Adorno conducted a study of the astrology column of a Los Angeles newspaper aspart of a project examining mass culture in capitalist society.:326 Adorno believed that popular astrology, as a device,invariably led to statements which encouraged conformity, and that astrologers who went against conformity withstatement discouraging performance at work etc. would risk losing their jobs.:327 Adorno concluded that astrologywas a large-scale manifestation of systematic irrationalism, where individuals were subtly being led to believe thatthe author of the column was addressing them directly through the use of flattery and vague generalisations. Adornodrew a parallel with the phrase opium of the people, by Karl Marx, by commenting "occultism is the metaphysic ofthe dopes".:329

A 2005 Gallup poll and a 2009 survey by the Pew Research Center reported that 25% of U.S. adults believe inastrology. According to data released in the National Science Foundation's 2014 Science and Engineering Indicatorsstudy, "Fewer Americans rejected astrology in 2012 than in recent years." The NSF study noted that in 2012,"slightly more than half of Americans said that astrology was 'not at all scientific,' whereas nearly two-thirds gavethis response in 2010. The comparable percentage has not been this low since 1983."

India and Japan

Astrology 15

Birth (in blue) and death (in red) rates of Japansince 1950, with the sudden drop in births during

hinoeuma year (1966)

In India, there is a long-established and widespread belief in astrology.It is commonly used for daily life, particularly in matters concerningmarriage and career, and makes extensive use of electional, horary andkarmic astrology. Indian politics have also been influenced byastrology. It is still considered a branch of the Vedanga.[51][52] In 2001,Indian scientists and politicians debated and critiqued a proposal to usestate money to fund research into astrology, resulting in permission forIndian universities to offer courses in Vedic astrology.

On February 2011, the Bombay High Court reaffirmed astrology'sstanding in India when it dismissed a case which had challenged itsstatus as a science.[53]

In Japan, a strong belief in astrology has led to dramatic changes in the fertility rate and the number of abortions inthe years of "Fire Horse". Women born in hinoeuma years are believed to be unmarriageable and to bring bad luck totheir father or husband. In 1966, the number of babies born in Japan dropped by over 25% as parents tried to avoidthe stigma of having a daughter born in the hinoeuma year.

Literature and music

Title page of John Lyly's astrologicalplay, The Woman in the Moon, 1597

The fourteenth-century English poets John Gower and Geoffrey Chaucer bothreferred to astrology in their works, including Gower's Confessio Amantis andChaucer's The Canterbury Tales. Chaucer commented explicitly on astrology inhis Treatise on the Astrolabe, demonstrating personal knowledge of one area,judicial astrology, with an account of how to find the ascendant or rising sign.[54]

In the fifteenth century, references to astrology, such as with similes, became "amatter of course" in English literature.

In the sixteenth century, John Lyly's 1597 play, The Woman in the Moon, iswholly motivated by astrology, while Christopher Marlowe makes astrologicalreferences in his plays Doctor Faustus and Tamburlaine (both c. 1590), and SirPhilip Sidney refers to astrology at least four times in his romance The Countessof Pembroke's Arcadia (c. 1580). Edmund Spenser uses astrology bothdecoratively and causally in his poetry, revealing "unmistakably an abidinginterest in the art, an interest shared by a large number of his contemporaries",while George Chapman's play Byron's Conspiracy (1608) similarly usesastrology as a causal mechanism in the drama. William Shakespeare's attitudetowards astrology is unclear, with contradictory references in plays including King Lear, Antony and Cleopatra, andRichard II. Shakespeare was familiar with astrology and made use of his knowledge of astrology "in nearly everyplay he wrote", assuming a basic familiarity with the subject in his commercial audience. Outside theatre, thephysician and mystic Robert Fludd practised astrology, as did the quack doctor Simon Forman. In ElizabethanEngland, "the usual feeling about astrology ... [was] that it is the most useful of the sciences".

The most famous piece of music to be influenced by astrology is the orchestral suite The Planets. Written by theBritish composer Gustav Holst (1874–1934), and first performed in 1918, the framework of The Planets is basedupon the astrological symbolism of the planets.[55] Each of the seven movements of the suite is based upon adifferent planet, though the movements are not in the order of the planets from the Sun. The composer ColinMatthews wrote an eighth movement entitled "Pluto, the Renewer", first performed in 2000. In 1937, another Britishcomposer, Constant Lambert, wrote a ballet on astrological themes, called Horoscope. In 1974, the New Zealandcomposer Edwin Carr wrote The Twelve Signs: An Astrological Entertainment for orchestra without strings.

Astrology 16

Notes[1] http:/ / en. wikipedia. org/ w/ index. php?title=Template:Ast_box& action=edit[2] Two texts which refer to the 'omens of Sargon' are reported in E. F. Weidner, 'Historiches Material in der Babyonischen Omina-Literatur'

Altorientalische Studien, ed. Bruno Meissner, (Leipzig, 1928-9), v. 231 and 236.[3] From scroll A of the ruler Gudea of Lagash, I 17 – VI 13. O. Kaiser, Texte aus der Umwelt des Alten Testaments, Bd. 2, 1–3. Gütersloh,

1986–1991. Also quoted in A. Falkenstein, 'Wahrsagung in der sumerischen Überlieferung', La divination en Mésopotamie ancienne et dansles régions voisines. Paris, 1966.

[4][4] Long, 2005. p. 173.[5] Long, 2005. pp. 173–174.[6][6] Long, 2005. p. 177.[7][7] Long, 2005. p. 174.[8][8] Long, 2005. p. 184.[9][9] Long, 2005. p. 186.[10][10] Barton, 1994. p. 24.[11] Holden, 1996. pp. 11–13.[12][12] Barton, 1994. p. 20.[13][13] Robbins, 1940. 'Introduction' p. xii.[14][14] Campion, 2008. p. 173.[15][15] Campion, 2008. p. 84.[16] Campion, 2008. pp. 173–174.[17][17] Barton, 1994. p. 32.[18] Barton, 1994. p. 32–33.[19] Campion, 2008. pp. 227–228.[20][20] Parker, 1983. p. 16.[21] Juvenal, Satire 6: The Ways of Women (http:/ / www. tertullian. org/ fathers/ juvenal_satires_06. htm) (translated by G. G. Ramsay, 1918,

retrieved 5 July 2012).[22][22] Barton, 1994. p. 43.[23][23] Barton, 1994. p. 63.[24][24] Campion, 1982. p. 44.[25][25] Campion, 1982. p. 45.[26][26] Campion, 1982. p. 46.[27][27] Wood, 1970. p. 5[28][28] Wood, 1970. p. 6[29] Wood, 1970. pp. 8–11[30][30] Veenstra, 1997. pp. 5, 32, passim[31][31] Veenstra, 1997. p. 184[32][32] Campion, 1982. p. 47.[33][33] Cummins A (2012) The Starry Rubric: Seventeenth-Century English Astrology and Magic, p. 3. France:Hadean Press[34] Cummins A (2012) The Starry Rubric: Seventeenth-Century English Astrology and Magic, p. 43–45. France:Hadean Press[35] Gieser, Suzanne. The Innermost Kernel, Depth Psychology and Quantum Physics. Wolfgang Pauli's Dialogue with C.G.Jung, (Springer,

Berlin, 2005) p. 21 ISBN 3-540-20856-9[36] Campion, Nicholas. "Prophecy, Cosmology and the New Age Movement. The Extent and Nature of Contemporary Belief in Astrology."(Bath

Spa University College, 2003) via Campion, Nicholas, History of Western Astrology, (Continuum Books, London & New York, 2009) pp.248, 256, ISBN 978-1-84725-224-1

[37][37] The New Encyclopædia Britannica, Encyclopædia Britannica,' v.5, 1974, p. 916[38] Dietrich, Thomas: 'The Origin of Culture and Civilization, Phenix & Phenix Literary Publicists, 2005, p. 305[39] James R. Lewis, 2003. The Astrology Book: the Encyclopedia of Heavenly Influences. Visible Ink Press. Online at Google Books.[40] F. Richard Stephenson, "Chinese Roots of Modern Astronomy", New Scientist, 26 June 1980. See also 二 十 八 宿 的 形 成 与 演 变

(http:/ / www. lamost. org/ ~yzhao/ history/ xiu28. html)[41] Theodora Lau, The Handbook of Chinese Horoscopes, pp 2–8, 30–5, 60–4, 88–94, 118–24, 148–53, 178–84, 208–13, 238–44, 270–78,

306–12, 338–44, Souvenir Press, New York, 2005[42][42] (in Thai)[43] Catarina Belo, Catarina Carriço Marques de Moura Belo, Chance and determinism in Avicenna and Averroës, p. 228. Brill, 2007. ISBN

90-04-15587-2.[44] George Saliba, Avicenna: 'viii. Mathematics and Physical Sciences'. Encyclopædia Iranica, Online Edition, 2011, available at http:/ / www.

iranicaonline. org/ articles/ avicenna-viii

• The Humanist (http:/ / thehumanist. org/ the-humanist-archive/ ), volume 36, no.5 (1976).[46] see Heuristics in judgement and decision making

Astrology 17

•• The relevant piece is also published in[48] My former student Shawn Carlson published in Nature magazine the definitive scientific test of Astrology.

"... a perfectly convincing and lasting demonstration."[49][49] Tester, 1999. Page 161.[50][50] Italics in original.[51] "In countries such as India, where only a small intellectual elite has been trained in Western physics, astrology manages to retain here and

there its position among the sciences." David Pingree and Robert Gilbert, "Astrology; Astrology In India; Astrology in modern times".Encyclopædia Britannica, 2008

[52] Mohan Rao, Female foeticide: where do we go? Indian Journal of Medical Ethics October–December 2001 9(4) (http:/ / web. archive. org/web/ 20101103000514/ http:/ / issuesinmedicalethics. org/ 094co123. html)

[53] 'Astrology is a science: Bombay HC', The Times of India (http:/ / timesofindia. indiatimes. com/ india/ Astrology-is-a-science-Bombay-HC/articleshow/ 7418795. cms), 3 February 2011

[54] Wood, 1970. pp.12–21[55] Campion, Nicholas.:A History of Western Astrology: Volume II: The Medieval and Modern Worlds. (Continuum Books, 2009) pp. 244–245

ISBN 978-1-84725-224-1

References

Sources• Barton, Tamsyn (1994). Ancient Astrology. Routledge. ISBN 0-415-11029-7.• Kay, Richard (1994). Dante's Christian Astrology. Middle Ages Series. University of Pennsylvania Press.• Campion, Nicholas (1982). An Introduction to the History of Astrology. ISCWA.• Holden, James Herschel (2006). A History of Horoscopic Astrology (2nd ed.). AFA. ISBN 0-86690-463-8.• Long, A.A. (2005). "6: Astrology: arguments pro and contra". In Barnes, Jonathan; Brunschwig, J. Science and

Speculation. Cambridge University Press. pp. 165–191.• Parker, Derek; Parker, Julia (1983). A history of astrology. Deutsch. ISBN 978-0-233-97576-4.• Robbins, Frank E., ed. (1940). Ptolemy Tetrabiblos. Harvard University Press (Loeb Classical Library).

ISBN 0-674-99479-5.• Veenstra, J.R. (1997). Magic and Divination at the Courts of Burgundy and France: Text and Context of Laurens

Pignon's "Contre les Devineurs" (1411). Brill. ISBN 978-90-04-10925-4.• Wedel, Theodore Otto (1920). The Mediæval Attitude Toward Astrology: Particularly in England (http:/ / archive.

org/ stream/ medivalattitud00wede#page/ n9/ mode/ 2up). Yale University Press.• Wood, Chauncey (1970). Chaucer and the Country of the Stars: Poetical Uses of Astrological Imagery. Princeton

University Press.

Further reading• Forer, Bertram R. (January 1949). "The Fallacy of Personal Validation: A Classroom Demonstration of

Gullibility" (http:/ / pt. scribd. com/ doc/ 105681300/ Forer-The-Fallacy-of-Personal-Validation-1949). TheJournal of Abnormal and Social Psychology 44 (1).

• Osborn, M. (2002). Time and the Astrolabe in The Canterbury Tales (http:/ / books. google. com/ books/ about/Time_and_the_astrolabe_in_the_Canterbury. html?id=twt6-FgU-EkC). University of Oklahoma Press.

• Thorndike, Lynn (1955). "The True Place of Astrology in the History of Science". Isis 46 (3).

Astrology 18

External links• Astrology (http:/ / www. dmoz. org/ Society/ Religion_and_Spirituality/ Divination/ Astrology/ ) at DMOZ• Digital International Astrology Library (http:/ / cura. free. fr/ DIAL. html) at International Astrology Research

Center

AstronomyThis article is about the scientific study of celestial objects. For other uses, see Astronomy (disambiguation).

A star-forming region in the Large MagellanicCloud, an irregular galaxy.

A giant Hubble mosaic of the Crab Nebula, asupernova remnant

Part of a series on

Science

•• Outline•• Portal•• Category

•• v•• t• e [1]

Astronomy is a natural science which is the study of celestial objects (such as stars, galaxies, planets, moons, andnebulae), the physics, chemistry, and evolution of such objects, and phenomena that originate outside the atmosphereof Earth, including supernovae explosions, gamma ray bursts, and cosmic microwave background radiation. Arelated but distinct subject, cosmology, is concerned with studying the universe as a whole.Astronomy is one of the oldest sciences. Prehistoric cultures have left astronomical artifacts such as the Egyptianmonuments and Nubian monuments, and early civilizations such as the Babylonians, Greeks, Chinese, Indians,Iranians and Maya performed methodical observations of the night sky. However, the invention of the telescope wasrequired before astronomy was able to develop into a modern science. Historically, astronomy has includeddisciplines as diverse as astrometry, celestial navigation, observational astronomy and the making of calendars, butprofessional astronomy is nowadays often considered to be synonymous with astrophysics.

Astronomy 19

During the 20th century, the field of professional astronomy split into observational and theoretical branches.Observational astronomy is focused on acquiring data from observations of astronomical objects, which is thenanalyzed using basic principles of physics. Theoretical astronomy is oriented toward the development of computer oranalytical models to describe astronomical objects and phenomena. The two fields complement each other, withtheoretical astronomy seeking to explain the observational results and observations being used to confirm theoreticalresults.Astronomy is one of the few sciences where amateurs can still play an active role, especially in the discovery andobservation of transient phenomena. Amateur astronomers have contributed to many important astronomicaldiscoveries.

Etymology

19th century Observatory Sydney, Australia(1872)

Astronomy (from the Greek words astron (ἄστρον), "star" and -nomiafrom nomos (νόμος), "law" or "culture") means "law of the stars" (or"culture of the stars" depending on the translation). Astronomy shouldnot be confused with astrology, the belief system which claims thathuman affairs are correlated with the positions of celestial objects.[2]

Although the two fields share a common origin they are now entirelydistinct.

Use of terms "astronomy" and "astrophysics"

Generally, either the term "astronomy" or "astrophysics" may be usedto refer to this subject. Based on strict dictionary definitions,"astronomy" refers to "the study of objects and matter outside theEarth's atmosphere and of their physical and chemical properties" and "astrophysics" refers to the branch ofastronomy dealing with "the behavior, physical properties, and dynamic processes of celestial objects andphenomena". In some cases, as in the introduction of the introductory textbook The Physical Universe by Frank Shu,"astronomy" may be used to describe the qualitative study of the subject, whereas "astrophysics" is used to describethe physics-oriented version of the subject. However, since most modern astronomical research deals with subjectsrelated to physics, modern astronomy could actually be called astrophysics. Few fields, such as astrometry, arepurely astronomy rather than also astrophysics. Various departments in which scientists carry out research on thissubject may use "astronomy" and "astrophysics," partly depending on whether the department is historicallyaffiliated with a physics department, and many professional astronomers have physics rather than astronomydegrees. One of the leading scientific journals in the field is the European journal named Astronomy andAstrophysics. The leading American journals are The Astrophysical Journal and The Astronomical Journal.

Astronomy 20

HistoryMain article: History of astronomyFurther information: Archaeoastronomy and List of astronomers

A celestial map from the 17th century, by theDutch cartographer Frederik de Wit.

In early times, astronomy only comprised the observation andpredictions of the motions of objects visible to the naked eye. In somelocations, such as Stonehenge, early cultures assembled massiveartifacts that possibly had some astronomical purpose. In addition totheir ceremonial uses, these observatories could be employed todetermine the seasons, an important factor in knowing when to plantcrops, as well as in understanding the length of the year.[3]

Before tools such as the telescope were invented, early study of thestars was conducted using the naked eye. As civilizations developed,most notably in Mesopotamia, China, Egypt, Greece, India, andCentral America, astronomical observatories were assembled, andideas on the nature of the universe began to be explored. Most of early astronomy actually consisted of mapping thepositions of the stars and planets, a science now referred to as astrometry. From these observations, early ideas aboutthe motions of the planets were formed, and the nature of the Sun, Moon and the Earth in the universe were exploredphilosophically. The Earth was believed to be the center of the universe with the Sun, the Moon and the stars rotatingaround it. This is known as the geocentric model of the universe, or the Ptolemaic system, named after Ptolemy.

A particularly important early development was the beginning of mathematical and scientific astronomy, whichbegan among the Babylonians, who laid the foundations for the later astronomical traditions that developed in manyother civilizations. The Babylonians discovered that lunar eclipses recurred in a repeating cycle known as a saros.

Greek equatorial sun dial, Alexandriaon the Oxus, present-day

Afghanistan 3rd–2nd century BCE.

Following the Babylonians, significant advances in astronomy were made inancient Greece and the Hellenistic world. Greek astronomy is characterized fromthe start by seeking a rational, physical explanation for celestial phenomena. Inthe 3rd century BC, Aristarchus of Samos estimated the size and distance of theMoon and Sun, and was the first to propose a heliocentric model of the solarsystem. In the 2nd century BC, Hipparchus discovered precession, calculated thesize and distance of the Moon and invented the earliest known astronomicaldevices such as the astrolabe. Hipparchus also created a comprehensive catalogof 1020 stars, and most of the constellations of the northern hemisphere derivefrom Greek astronomy.[4] The Antikythera mechanism (c. 150–80 BC) was anearly analog computer designed to calculate the location of the Sun, Moon, andplanets for a given date. Technological artifacts of similar complexity did notreappear until the 14th century, when mechanical astronomical clocks appeared in Europe.

During the Middle Ages, astronomy was mostly stagnant in medieval Europe, at least until the 13th century.However, astronomy flourished in the Islamic world and other parts of the world. This led to the emergence of thefirst astronomical observatories in the Muslim world by the early 9th century.[5] In 964, the Andromeda Galaxy, thelargest galaxy in the Local Group, was discovered by the Persian astronomer Azophi and first described in his Bookof Fixed Stars. The SN 1006 supernova, the brightest apparent magnitude stellar event in recorded history, wasobserved by the Egyptian Arabic astronomer Ali ibn Ridwan and the Chinese astronomers in 1006. Some of theprominent Islamic (mostly Persian and Arab) astronomers who made significant contributions to the science includeAl-Battani, Thebit, Azophi, Albumasar, Biruni, Arzachel, Al-Birjandi, and the astronomers of the Maragheh and

Astronomy 21

Samarkand observatories. Astronomers during that time introduced many Arabic names now used for individualstars. It is also believed that the ruins at Great Zimbabwe and Timbuktu may have housed an astronomicalobservatory. Europeans had previously believed that there had been no astronomical observation in pre-colonialMiddle Ages sub-Saharan Africa but modern discoveries show otherwise.[6]

Scientific revolution

Galileo's sketches and observationsof the Moon revealed that the surface

was mountainous.

During the Renaissance, Nicolaus Copernicus proposed a heliocentric model ofthe solar system. His work was defended, expanded upon, and corrected byGalileo Galilei and Johannes Kepler. Galileo used telescopes to enhance hisobservations.

Kepler was the first to devise a system that described correctly the details of themotion of the planets with the Sun at the center. However, Kepler did notsucceed in formulating a theory behind the laws he wrote down.[7] It was left toNewton's invention of celestial dynamics and his law of gravitation to finallyexplain the motions of the planets. Newton also developed the reflectingtelescope.[]

Further discoveries paralleled the improvements in the size and quality of thetelescope. More extensive star catalogues were produced by Lacaille. Theastronomer William Herschel made a detailed catalog of nebulosity and clusters,and in 1781 discovered the planet Uranus, the first new planet found.[8] Thedistance to a star was first announced in 1838 when the parallax of 61 Cygni wasmeasured by Friedrich Bessel.[9]

During the 18–19th centuries, attention to the three body problem by Euler, Clairaut, and D'Alembert led to moreaccurate predictions about the motions of the Moon and planets. This work was further refined by Lagrange andLaplace, allowing the masses of the planets and moons to be estimated from their perturbations.[10]

Significant advances in astronomy came about with the introduction of new technology, including the spectroscopeand photography. Fraunhofer discovered about 600 bands in the spectrum of the Sun in 1814–15, which, in 1859,Kirchhoff ascribed to the presence of different elements. Stars were proven to be similar to the Earth's own Sun, butwith a wide range of temperatures, masses, and sizes.The existence of the Earth's galaxy, the Milky Way, as a separate group of stars, was only proved in the 20th century,along with the existence of "external" galaxies, and soon after, the expansion of the Universe, seen in the recessionof most galaxies from us. Modern astronomy has also discovered many exotic objects such as quasars, pulsars,blazars, and radio galaxies, and has used these observations to develop physical theories which describe some ofthese objects in terms of equally exotic objects such as black holes and neutron stars. Physical cosmology made hugeadvances during the 20th century, with the model of the Big Bang heavily supported by the evidence provided byastronomy and physics, such as the cosmic microwave background radiation, Hubble's law, and cosmologicalabundances of elements. Space telescopes have enabled measurements in parts of the electromagnetic spectrumnormally blocked or blurred by the atmosphere.

Astronomy 22

Observational astronomyMain article: Observational astronomyIn astronomy, the main source of information about celestial bodies and other objects is visible light or moregenerally electromagnetic radiation. Observational astronomy may be divided according to the observed region ofthe electromagnetic spectrum. Some parts of the spectrum can be observed from the Earth's surface, while other partsare only observable from either high altitudes or outside the earth's atmosphere. Specific information on thesesubfields is given below.

Radio astronomy

The Very Large Array in New Mexico, anexample of a radio telescope

Main article: Radio astronomyRadio astronomy studies radiation with wavelengths greater thanapproximately one millimeter. Radio astronomy is different from mostother forms of observational astronomy in that the observed radiowaves can be treated as waves rather than as discrete photons. Hence, itis relatively easier to measure both the amplitude and phase of radiowaves, whereas this is not as easily done at shorter wavelengths.

Although some radio waves are produced by astronomical objects inthe form of thermal emission, most of the radio emission that isobserved from Earth is the result of synchrotron radiation, which isproduced when electrons orbit magnetic fields. Additionally, a numberof spectral lines produced by interstellar gas, notably the hydrogen spectral line at 21 cm, are observable at radiowavelengths.

A wide variety of objects are observable at radio wavelengths, including supernovae, interstellar gas, pulsars, andactive galactic nuclei.

Infrared astronomyMain article: Infrared astronomy

ALMA Observatory is one of the highestobservatory sites on Earth.

Infrared astronomy is founded on the detection and analysis of infraredradiation (wavelengths longer than red light). The infrared spectrum isuseful for studying objects that are too cold to radiate visible light,such as planets, circumstellar disks or nebulae whose light is blockedby dust. Longer infrared wavelengths can penetrate clouds of dust thatblock visible light, allowing the observation of young stars inmolecular clouds and the cores of galaxies. Observations from theWide-field Infrared Survey Explorer (WISE) have been particularly effective at unveiling numerous Galacticprotostars and their host star clusters.[11] With the exception of wavelengths close to visible light, infrared radiationis heavily absorbed by the atmosphere, or masked, as the atmosphere itself produces significant infrared emission.Consequently, infrared observatories have to be located in high, dry places or in space. Some molecules radiatestrongly in the infrared. This allows the study the chemistry of space; more specifically it can detect water in comets.

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Optical astronomy

The Subaru Telescope (left) and KeckObservatory (center) on Mauna Kea, both

examples of an observatory that operates atnear-infrared and visible wavelengths. The

NASA Infrared Telescope Facility (right) is anexample of a telescope that operates only at

near-infrared wavelengths.

Main article: Optical astronomyHistorically, optical astronomy, also called visible light astronomy, isthe oldest form of astronomy. Optical images of observations wereoriginally drawn by hand. In the late 19th century and most of the 20thcentury, images were made using photographic equipment. Modernimages are made using digital detectors, particularly detectors usingcharge-coupled devices (CCDs) and recorded on modern medium.Although visible light itself extends from approximately 4000 Å to7000 Å (400 nm to 700 nm), that same equipment can be used toobserve some near-ultraviolet and near-infrared radiation.

Ultraviolet astronomy

Main article: Ultraviolet astronomyUltraviolet astronomy refers to observations at ultraviolet wavelengthsbetween approximately 100 and 3200 Å (10 to 320 nm). Light at these wavelengths is absorbed by the Earth'satmosphere, so observations at these wavelengths must be performed from the upper atmosphere or from space.Ultraviolet astronomy is best suited to the study of thermal radiation and spectral emission lines from hot blue stars(OB stars) that are very bright in this wave band. This includes the blue stars in other galaxies, which have been thetargets of several ultraviolet surveys. Other objects commonly observed in ultraviolet light include planetarynebulae, supernova remnants, and active galactic nuclei. However, as ultraviolet light is easily absorbed byinterstellar dust, an appropriate adjustment of ultraviolet measurements is necessary.

X-ray astronomyMain article: X-ray astronomyX-ray astronomy is the study of astronomical objects at X-ray wavelengths. Typically, X-ray radiation is producedby synchrotron emission (the result of electrons orbiting magnetic field lines), thermal emission from thin gasesabove 107 (10 million) kelvins, and thermal emission from thick gases above 107 Kelvin. Since X-rays are absorbedby the Earth's atmosphere, all X-ray observations must be performed from high-altitude balloons, rockets, orspacecraft. Notable X-ray sources include X-ray binaries, pulsars, supernova remnants, elliptical galaxies, clusters ofgalaxies, and active galactic nuclei.X-rays were first observed and documented in 1895 by Wilhelm Conrad Röntgen, a German scientist who foundthem when experimenting with vacuum tubes. Through a series of experiments, Röntgen was able to discover thebeginning elements of radiation. The "X", in fact, holds its own significance, as it represents Röntgen's inability toidentify exactly the type of radiation.

Gamma-ray astronomyMain article: Gamma ray astronomyGamma ray astronomy is the study of astronomical objects at the shortest wavelengths of the electromagneticspectrum. Gamma rays may be observed directly by satellites such as the Compton Gamma Ray Observatory or byspecialized telescopes called atmospheric Cherenkov telescopes. The Cherenkov telescopes do not actually detect thegamma rays directly but instead detect the flashes of visible light produced when gamma rays are absorbed by theEarth's atmosphere.

Astronomy 24

Most gamma-ray emitting sources are actually gamma-ray bursts, objects which only produce gamma radiation for afew milliseconds to thousands of seconds before fading away. Only 10% of gamma-ray sources are non-transientsources. These steady gamma-ray emitters include pulsars, neutron stars, and black hole candidates such as activegalactic nuclei.

Fields not based on the electromagnetic spectrumIn addition to electromagnetic radiation, a few other events originating from great distances may be observed fromthe Earth.In neutrino astronomy, astronomers use heavily shielded underground facilities such as SAGE, GALLEX, andKamioka II/III for the detection of neutrinos. The vast majority of the neutrinos streaming through the earth originatefrom the Sun, but 24 neutrinos were also detected from supernova 1987A. Cosmic rays, which consist of very highenergy particles that can decay or be absorbed when they enter the Earth's atmosphere, result in a cascade of particleswhich can be detected by current observatories. Additionally, some future neutrino detectors may also be sensitive tothe particles produced when cosmic rays hit the Earth's atmosphere.Gravitational wave astronomy is an emerging new field of astronomy which aims to use gravitational wave detectorsto collect observational data about compact objects. A few observatories have been constructed, such as the LaserInterferometer Gravitational Observatory LIGO, but gravitational waves are extremely difficult to detect.Combining observations made using electromagnetic radiation, neutrinos or gravitational waves with those madeusing a different means, which shall give complementary information, is known as multi-messenger astronomy.[12]

Astrometry and celestial mechanicsMain articles: Astrometry and Celestial mechanicsOne of the oldest fields in astronomy, and in all of science, is the measurement of the positions of celestial objects.Historically, accurate knowledge of the positions of the Sun, Moon, planets and stars has been essential in celestialnavigation (the use of celestial objects to guide navigation) and in the making of calendars.Careful measurement of the positions of the planets has led to a solid understanding of gravitational perturbations,and an ability to determine past and future positions of the planets with great accuracy, a field known as celestialmechanics. More recently the tracking of near-Earth objects will allow for predictions of close encounters, andpotential collisions, with the Earth.The measurement of stellar parallax of nearby stars provides a fundamental baseline in the cosmic distance ladderthat is used to measure the scale of the universe. Parallax measurements of nearby stars provide an absolute baselinefor the properties of more distant stars, as their properties can be compared. Measurements of radial velocity andproper motion plot the movement of these systems through the Milky Way galaxy. Astrometric results are the basisused to calculate the distribution of dark matter in the galaxy.During the 1990s, the measurement of the stellar wobble of nearby stars was used to detect large extrasolar planetsorbiting nearby stars.

Theoretical astronomy

Astronomy 25

Nucleosynthesis

•• Stellar nucleosynthesis•• Big Bang nucleosynthesis•• Supernova nucleosynthesis•• Cosmic ray spallation

Related topics

•• Astrophysics•• Nuclear fusion

•• R-process•• S-process

•• Nuclear fission

•• v•• t• e [13]

Main article: Theoretical astronomyTheoretical astronomers use several tools including analytical models (for example, polytropes to approximate thebehaviors of a star) and computational numerical simulations. Each has some advantages. Analytical models of aprocess are generally better for giving insight into the heart of what is going on. Numerical models reveal theexistence of phenomena and effects otherwise unobserved.Theorists in astronomy endeavor to create theoretical models and from the results predict observationalconsequences of those models. The observation of a phenomenon predicted by a model allows astronomers to selectbetween several alternate or conflicting models.Theorists also try to generate or modify models to take into account new data. In the case of an inconsistency, thegeneral tendency is to try to make minimal modifications to the model so that it produces results that fit the data. Insome cases, a large amount of inconsistent data over time may lead to total abandonment of a model.Topics studied by theoretical astronomers include: stellar dynamics and evolution; galaxy formation; large-scalestructure of matter in the Universe; origin of cosmic rays; general relativity and physical cosmology, including stringcosmology and astroparticle physics. Astrophysical relativity serves as a tool to gauge the properties of large scalestructures for which gravitation plays a significant role in physical phenomena investigated and as the basis for blackhole (astro)physics and the study of gravitational waves.Some widely accepted and studied theories and models in astronomy, now included in the Lambda-CDM model arethe Big Bang, Cosmic inflation, dark matter, and fundamental theories of physics.A few examples of this process:

Astronomy 26

Physical process Experimental tool Theoretical model Explains/predicts

Gravitation Radio telescopes Self-gravitating system Emergence of a star system

Nuclear fusion Spectroscopy Stellar evolution How the stars shine and how metals formed

The Big Bang Hubble Space Telescope, COBE Expanding universe Age of the Universe

Quantum fluctuations Cosmic inflation Flatness problem

Gravitational collapse X-ray astronomy General relativity Black holes at the center of Andromeda galaxy

CNO cycle in stars The dominant source of energy for massive star.

Dark matter and dark energy are the current leading topics in astronomy, as their discovery and controversyoriginated during the study of the galaxies.

Specific subfields

Solar astronomy

An ultraviolet image of the Sun's activephotosphere as viewed by the TRACE space

telescope. NASA photo

Solar observatory Lomnický štít (Slovakia) builtin 1962.

Main article: SunSee also: Solar telescopeAt a distance of about eight light-minutes, the most frequently studiedstar is the Sun, a typical main-sequence dwarf star of stellar class G2V, and about 4.6 billion years (Gyr) old. The Sun is not considered avariable star, but it does undergo periodic changes in activity known asthe sunspot cycle. This is an 11-year fluctuation in sunspot numbers.Sunspots are regions of lower-than- average temperatures that areassociated with intense magnetic activity.

The Sun has steadily increased in luminosity over the course of its life,increasing by 40% since it first became a main-sequence star. The Sunhas also undergone periodic changes in luminosity that can have asignificant impact on the Earth. The Maunder minimum, for example,is believed to have caused the Little Ice Age phenomenon during theMiddle Ages.

The visible outer surface of the Sun is called the photosphere. Abovethis layer is a thin region known as the chromosphere. This issurrounded by a transition region of rapidly increasing temperatures,and finally by the super-heated corona.

At the center of the Sun is the core region, a volume of sufficienttemperature and pressure for nuclear fusion to occur. Above the core isthe radiation zone, where the plasma conveys the energy flux by meansof radiation. Above that are the outer layers that form a convectionzone where the gas material transports energy primarily throughphysical displacement of the gas. It is believed that this convectionzone creates the magnetic activity that generates sun spots.

A solar wind of plasma particles constantly streams outward from the Sun until, at the outermost limit of the solar system, it reaches the heliopause. This solar wind interacts with the magnetosphere of the Earth to create the Van Allen radiation belts about the Earth, as well as the aurora where the lines of the Earth's magnetic field descend into

Astronomy 27

the atmosphere.

Planetary scienceMain articles: Planetary science and Planetary geologyPlanetary science is the study of the assemblage of planets, moons, dwarf planets, comets, asteroids, and other bodiesorbiting the Sun, as well as extrasolar planets. The Solar System has been relatively well-studied, initially throughtelescopes and then later by spacecraft. This has provided a good overall understanding of the formation andevolution of this planetary system, although many new discoveries are still being made.

The black spot at the top is a dust devil climbinga crater wall on Mars. This moving, swirling

column of Martian atmosphere (comparable to aterrestrial tornado) created the long, dark streak.

NASA image.

The Solar System is subdivided into the inner planets, the asteroid belt,and the outer planets. The inner terrestrial planets consist of Mercury,Venus, Earth, and Mars. The outer gas giant planets are Jupiter, Saturn,Uranus, and Neptune. Beyond Neptune lies the Kuiper Belt, and finallythe Oort Cloud, which may extend as far as a light-year.

The planets were formed in the protoplanetary disk that surrounded theearly Sun. Through a process that included gravitational attraction,collision, and accretion, the disk formed clumps of matter that, withtime, became protoplanets. The radiation pressure of the solar windthen expelled most of the unaccreted matter, and only those planetswith sufficient mass retained their gaseous atmosphere. The planetscontinued to sweep up, or eject, the remaining matter during a period of intense bombardment, evidenced by themany impact craters on the Moon. During this period, some of the protoplanets may have collided, the leadinghypothesis for how the Moon was formed.

Once a planet reaches sufficient mass, the materials of different densities segregate within, during planetarydifferentiation. This process can form a stony or metallic core, surrounded by a mantle and an outer surface. The coremay include solid and liquid regions, and some planetary cores generate their own magnetic field, which can protecttheir atmospheres from solar wind stripping.[14]

A planet or moon's interior heat is produced from the collisions that created the body, radioactive materials (e.g.uranium, thorium, and 26Al), or tidal heating. Some planets and moons accumulate enough heat to drive geologicprocesses such as volcanism and tectonics. Those that accumulate or retain an atmosphere can also undergo surfaceerosion from wind or water. Smaller bodies, without tidal heating, cool more quickly; and their geological activityceases with the exception of impact cratering.

Stellar astronomy

The Ant planetary nebula. Ejecting gas from thedying central star shows symmetrical patterns

unlike the chaotic patterns of ordinary explosions.

Main article: StarThe study of stars and stellar evolution is fundamental to ourunderstanding of the universe. The astrophysics of stars has beendetermined through observation and theoretical understanding; andfrom computer simulations of the interior.[15] Star formation occurs indense regions of dust and gas, known as giant molecular clouds. Whendestabilized, cloud fragments can collapse under the influence ofgravity, to form a protostar. A sufficiently dense, and hot, core regionwill trigger nuclear fusion, thus creating a main-sequence star.

Almost all elements heavier than hydrogen and helium were createdinside the cores of stars.

Astronomy 28

The characteristics of the resulting star depend primarily upon its starting mass. The more massive the star, thegreater its luminosity, and the more rapidly it expends the hydrogen fuel in its core. Over time, this hydrogen fuel iscompletely converted into helium, and the star begins to evolve. The fusion of helium requires a higher coretemperature, so that the star both expands in size, and increases in core density. The resulting red giant enjoys a brieflife span, before the helium fuel is in turn consumed. Very massive stars can also undergo a series of decreasingevolutionary phases, as they fuse increasingly heavier elements.[16]

The final fate of the star depends on its mass, with stars of mass greater than about eight times the Sun becomingcore collapse supernovae;[17] while smaller stars form a white dwarf as it ejects matter that forms a planetarynebulae.[18] The remnant of a supernova is a dense neutron star, or, if the stellar mass was at least three times that ofthe Sun, a black hole. Close binary stars can follow more complex evolutionary paths, such as mass transfer onto awhite dwarf companion that can potentially cause a supernova.[19] Planetary nebulae and supernovae are necessaryfor the distribution of metals to the interstellar medium; without them, all new stars (and their planetary systems)would be formed from hydrogen and helium alone.[20]

See also: Solar astronomy

Galactic astronomy

Observed structure of the Milky Way's spiralarms

Main article: Galactic astronomyOur solar system orbits within the Milky Way, a barred spiral galaxythat is a prominent member of the Local Group of galaxies. It is arotating mass of gas, dust, stars and other objects, held together bymutual gravitational attraction. As the Earth is located within the dustyouter arms, there are large portions of the Milky Way that are obscuredfrom view.

In the center of the Milky Way is the core, a bar-shaped bulge withwhat is believed to be a supermassive black hole at the center. This issurrounded by four primary arms that spiral from the core. This is aregion of active star formation that contains many younger, populationI stars. The disk is surrounded by a spheroid halo of older, populationII stars, as well as relatively dense concentrations of stars known as globular clusters.

Between the stars lies the interstellar medium, a region of sparse matter. In the densest regions, molecular clouds ofmolecular hydrogen and other elements create star-forming regions. These begin as a compact pre-stellar core ordark nebulae, which concentrate and collapse (in volumes determined by the Jeans length) to form compactprotostars.As the more massive stars appear, they transform the cloud into an H II region (ionized atomic hydrogen) of glowinggas and plasma. The stellar wind and supernova explosions from these stars eventually cause the cloud to disperse,often leaving behind one or more young open clusters of stars. These clusters gradually disperse, and the stars jointhe population of the Milky Way.Kinematic studies of matter in the Milky Way and other galaxies have demonstrated that there is more mass than canbe accounted for by visible matter. A dark matter halo appears to dominate the mass, although the nature of this darkmatter remains undetermined.

Astronomy 29

Extragalactic astronomy

This image shows several blue, loop-shapedobjects that are multiple images of the same

galaxy, duplicated by the gravitational lens effectof the cluster of yellow galaxies near the middleof the photograph. The lens is produced by thecluster's gravitational field that bends light to

magnify and distort the image of a more distantobject.

Main article: Extragalactic astronomyThe study of objects outside our galaxy is a branch of astronomyconcerned with the formation and evolution of Galaxies; theirmorphology (description) and classification; and the observation ofactive galaxies, and at a larger scale, the groups and clusters ofgalaxies. Finally, the latter is important for the understanding of thelarge-scale structure of the cosmos.

Most galaxies are organized into distinct shapes that allow forclassification schemes. They are commonly divided into spiral,elliptical and Irregular galaxies.

As the name suggests, an elliptical galaxy has the cross-sectional shapeof an ellipse. The stars move along random orbits with no preferreddirection. These galaxies contain little or no interstellar dust; fewstar-forming regions; and generally older stars. Elliptical galaxies aremore commonly found at the core of galactic clusters, and may havebeen formed through mergers of large galaxies.

A spiral galaxy is organized into a flat, rotating disk, usually with aprominent bulge or bar at the center, and trailing bright arms that spiraloutward. The arms are dusty regions of star formation where massive young stars produce a blue tint. Spiral galaxiesare typically surrounded by a halo of older stars. Both the Milky Way and our nearest galaxy neighbor, theAndromeda Galaxy, are spiral galaxies.

Irregular galaxies are chaotic in appearance, and are neither spiral nor elliptical. About a quarter of all galaxies areirregular, and the peculiar shapes of such galaxies may be the result of gravitational interaction.An active galaxy is a formation that emitts a significant amount of its energy from a source other than its stars, dustand gas. It is powered by a compact region at the core, thought to be a super-massive black hole that is emittingradiation from in-falling material.A radio galaxy is an active galaxy that is very luminous in the radio portion of the spectrum, and is emittingimmense plumes or lobes of gas. Active galaxies that emit shorter frequency, high-energy radiation include Seyfertgalaxies, Quasars, and Blazars. Quasars are believed to be the most consistently luminous objects in the knownuniverse.The large-scale structure of the cosmos is represented by groups and clusters of galaxies. This structure is organizedinto a hierarchy of groupings, with the largest being the superclusters. The collective matter is formed into filamentsand walls, leaving large voids between.

Astronomy 30

CosmologyMain article: Physical cosmology

Hubble Extreme Deep Field.

Cosmology (from the Greek κόσμος(kosmos) "world, universe" and λόγος(logos) "word, study" or literally "logic")could be considered the study of theuniverse as a whole.

Observations of the large-scale structure ofthe universe, a branch known as physicalcosmology, have provided a deepunderstanding of the formation andevolution of the cosmos. Fundamental tomodern cosmology is the well-acceptedtheory of the big bang, wherein our universebegan at a single point in time, andthereafter expanded over the course of 13.8billion years to its present condition. Theconcept of the big bang can be traced backto the discovery of the microwavebackground radiation in 1965.

In the course of this expansion, the universe underwent several evolutionary stages. In the very early moments, it istheorized that the universe experienced a very rapid cosmic inflation, which homogenized the starting conditions.Thereafter, nucleosynthesis produced the elemental abundance of the early universe. (See alsonucleocosmochronology.)

When the first neutral atoms formed from a sea of primordial ions, space became transparent to radiation, releasingthe energy viewed today as the microwave background radiation. The expanding universe then underwent a DarkAge due to the lack of stellar energy sources.A hierarchical structure of matter began to form from minute variations in the mass density of space. Matteraccumulated in the densest regions, forming clouds of gas and the earliest stars, the Population III stars. Thesemassive stars triggered the reionization process and are believed to have created many of the heavy elements in theearly universe, which, through nuclear decay, create lighter elements, allowing the cycle of nucleosynthesis tocontinue longer.[21]

Gravitational aggregations clustered into filaments, leaving voids in the gaps. Gradually, organizations of gas anddust merged to form the first primitive galaxies. Over time, these pulled in more matter, and were often organizedinto groups and clusters of galaxies, then into larger-scale superclusters.Fundamental to the structure of the universe is the existence of dark matter and dark energy. These are now thoughtto be its dominant components, forming 96% of the mass of the universe. For this reason, much effort is expended intrying to understand the physics of these components.

Astronomy 31

Interdisciplinary studiesAstronomy and astrophysics have developed significant interdisciplinary links with other major scientific fields.Archaeoastronomy is the study of ancient or traditional astronomies in their cultural context, utilizing archaeologicaland anthropological evidence. Astrobiology is the study of the advent and evolution of biological systems in theuniverse, with particular emphasis on the possibility of non-terrestrial life. Astrostatistics is the application ofstatistics to astrophysics to the analysis of vast amount of observational astrophysical data.The study of chemicals found in space, including their formation, interaction and destruction, is calledastrochemistry. These substances are usually found in molecular clouds, although they may also appear in lowtemperature stars, brown dwarfs and planets. Cosmochemistry is the study of the chemicals found within the SolarSystem, including the origins of the elements and variations in the isotope ratios. Both of these fields represent anoverlap of the disciplines of astronomy and chemistry. As "forensic astronomy", finally, methods from astronomyhave been used to solve problems of law and history.

Amateur astronomy

Amateur astronomers can build theirown equipment, and can hold star

parties and gatherings, such asStellafane.

Main article: Amateur astronomyAstronomy is one of the sciences to which amateurs can contribute the most.Collectively, amateur astronomers observe a variety of celestial objects andphenomena sometimes with equipment that they build themselves. Commontargets of amateur astronomers include the Moon, planets, stars, comets, meteorshowers, and a variety of deep-sky objects such as star clusters, galaxies, andnebulae. Astronomy clubs are located throughout the world and many haveprograms to help their members set up and complete observational programsincluding those to observe all the objects in the Messier (110 objects) or Herschal400 catalogues of points of interest in the night sky. One branch of amateurastronomy, amateur astrophotography, involves the taking of photos of the nightsky. Many amateurs like to specialize in the observation of particular objects,types of objects, or types of events which interest them.

Most amateurs work at visible wavelengths, but a small minority experimentwith wavelengths outside the visible spectrum. This includes the use of infraredfilters on conventional telescopes, and also the use of radio telescopes. The pioneer of amateur radio astronomy wasKarl Jansky, who started observing the sky at radio wavelengths in the 1930s. A number of amateur astronomers useeither homemade telescopes or use radio telescopes which were originally built for astronomy research but which arenow available to amateurs (e.g. the One-Mile Telescope).

Amateur astronomers continue to make scientific contributions to the field of astronomy and it is one of the fewscientific disciplines where amateurs can still make significant contributions. Amateurs can make occultationmeasurements that are used to refine the orbits of minor planets. They can also discover comets, and perform regularobservations of variable stars. There are hundreds of local astronomy clubs throughout the world and many help theirmembers set up and complete observational programs such as ones to observe all the Messier or Hershel catalogueobjects.Improvements in digital technology have allowed amateurs to make impressive advances in the field ofastrophotography.

Astronomy 32

Unsolved problems in astronomySee also: Unsolved problems in physicsAlthough the scientific discipline of astronomy has made tremendous strides in understanding the nature of theuniverse and its contents, there remain some important unanswered questions. Answers to these may require theconstruction of new ground- and space-based instruments, and possibly new developments in theoretical andexperimental physics.• What is the origin of the stellar mass spectrum? That is, why do astronomers observe the same distribution of

stellar masses – the initial mass function – apparently regardless of the initial conditions? A deeper understandingof the formation of stars and planets is needed.

• Is there other life in the Universe? Especially, is there other intelligent life? If so, what is the explanation for theFermi paradox? The existence of life elsewhere has important scientific and philosophical implications. Is theSolar System normal or atypical?

• What caused the Universe to form? Is the premise of the Fine-tuned universe hypothesis correct? If so, could thisbe the result of cosmological natural selection? What caused the cosmic inflation that produced our homogeneousuniverse? Why is there a baryon asymmetry?

• What is the nature of dark matter and dark energy? These dominate the evolution and fate of the cosmos, yet theirtrue nature remains unknown. What will be the ultimate fate of the universe?

•• How did the first galaxies form? How did supermassive black holes form?• What is creating the ultra-high-energy cosmic rays?

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[3][3] Forbes, 1909[4] Thurston, H., Early Astronomy. (http:/ / books. google. com/ books?id=rNpHjqxQQ9oC& pg=PA2) Springer, 1996. ISBN 0-387-94822-8 p.

2[5][5] , in[6][6] Stenger, Richard . CNN. 5 December 2002. Retrieved on 30 December 2011.[7] Forbes, 1909, pp. 49–58[8] Forbes, 1909, pp. 79–81[9] Forbes, 1909, pp. 147–150[10] Forbes, 1909, pp. 74–76[11] Majaess, D. (2013). Discovering protostars and their host clusters via WISE (http:/ / adsabs. harvard. edu/ abs/ 2013Ap& SS. 344. . 175M),

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Astronomy 33

Bibliography• Forbes, George (1909). History of Astronomy. London: Plain Label Books. ISBN 1-60303-159-6. Available at

Project Gutenberg (http:/ / www. gutenberg. org/ etext/ 8172), Google books (http:/ / books. google. com/books?id=hcLXcpUDqPgC& printsec=frontcover)

• Harpaz, Amos (1994). Stellar Evolution (http:/ / books. google. com/ ?id=kd4VEZv8oo0C& dq). A K Peters, Ltd.ISBN 978-1-56881-012-6.• Unsöld, A.; Baschek, B. (2001). The New Cosmos: An Introduction to Astronomy and Astrophysics. Springer.

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the American Institute of Physics• Southern Hemisphere Astronomy (http:/ / www. astronomy. net. nz)• Celestia Motherlode (http:/ / www. celestiamotherlode. net/ catalog/ educational. php/ ) Educational site for

Astronomical journeys through space• Prof. Sir Harry Kroto, NL (http:/ / www. vega. org. uk/ video/ subseries/ 16), Astrophysical Chemistry Lecture

Series. 8 Freeview Lectures provided by the Vega Science Trust.• Core books (http:/ / ads. harvard. edu/ books/ clab/ ) and core journals (http:/ / ads. harvard. edu/ books/ claj/ ) in

Astronomy, from the Smithsonian/NASA Astrophysics Data System• A Journey with Fred Hoyle: Second Edition (http:/ / www. worldscientific. com/ worldscibooks/ 10. 1142/ 8622),

by Chandra Wickramasinghe.

Article Sources and Contributors 34

Article Sources and ContributorsAstrology  Source: http://en.wikipedia.org/w/index.php?oldid=621434432  Contributors: ***Ria777, 0101LOcw, 100110100, 12text12, 167.154.11.xxx, 192.146.101.xxx, 1c33y37,209.31.208.xxx, 2over0, 55asdd, 66.77.80.xxx, 97198, 999, A bit iffy, A purple wikiuser, ALargeElk, Aaron Brenneman, Aaron Kauppi, Aaron Schulz, Academic Challenger, Acampbell70,Achillu, Achowat, Adambiswanger1, Addshore, Adeneus, Adraeus, Aeon2012, Aeternus, Afterwriting, Againme, Agge1000, Ahm2307, Ahoerstemeier, Aiko, Al E., Alai, Alan Liefting, AlanPeakall, Alansohn, Alarbus, Albertindian2001, Alcmaeonid, Alegoo92, Alensha, AlexR, Alfio, Ali the Munificent, All Is One, Aluracein82, Alvahir, Amakuru, Amalthea, Amitranjanamit,Amitsystem, Anarcham, Andonic, Andrei Rublev, Andres, Andrew Homer, Andrewpmk, AndyTheGrump, Anetode, Angeldeb82, Angry Python, Angryapathy, Ankit4321, Ann Stouter, Annur,Antandrus, Anupamjolly, Anuragblogger, Anypodetos, Apagogeron, Aphaia, Apola, Aquageek 22, Aquarius Rising, Aquarius rising, Aquirata, Ardeo, Arielastrology, Arousingeyehole,Arrow740, Art Carlson, Arthur Warrington Thomas, ArtifexMayhem, Artw, Asenine, Ashami, Ashenai, Ashley Y, Ashra enchantments, Askganesha, AstroChemist, AstroNomer, Astrobhadauria,Astrochologist13, Astrofaces, Astrolog, Astrologbg, Astrologist, AstrologyIsStupid, AstrologyIsVeryStupid, AstrologyIsVeryVeryStupid, Astrologyisrubbish, Astromaze, Astrosutraindia,Atethnekos, Avenash, Avoratio, AxelBoldt, AxelHarvey, B00P, BD2412, BIsopp, BadSeed, Balancer, Barek, BarretB, Bastique, Bcatt, Bcrowell, Becritical, Beetstra, Bellerophon,Benandorsqueaks, Bercg, Berlin Stark, Bgwhite, Bharat6663, BiT, Bihco, Bill Thayer, Billbike, Binerman, Binksternet, Bishonen, Bissinger, Blackcats, Bladesmulti, Blainster, Bless sins, Blink2008, BlinkingBlimey, Bmorton3, BobMak, Bobblewik, Bobo192, Bobrayner, Bodnotbod, Bongwarrior, Bookmarc, BorgQueen, Borislav, BradBeattie, Bradeos Graphon, Brandmeister,Brandmeister (old), BreakfastJr, Brian, Brianbryant, Bricology, Britmax, Brockert, Brossow, Bruce Millard, Bryan Derksen, Bsimmons666, Bubba73, Buddhipriya, Budfin, BullRangifer,Burlywood, Bwalls93, Byelf2007, Bzzzzzzzzster, C6541, CALR, CIreland, CJLL Wright, Caerwine, Calabe1992, Calton, CambridgeBayWeather, CanadianCaesar, CanadianLinuxUser,CapitalElll, Captain Disdain, Cardiffajax, Cardsharque, Carl T, Casanova, Casper2k3, Causa sui, Cazamic, Cazimi, Centrx, Cgosh, Chemist3456, Chesseball97, Chimpa, Chiswick Chap, ChrisBrennan, ChrisGualtieri, Chuck SMITH, Cicciostar, Ciuboda, Cjcooper, ClamDip, ClovisPt, Cmicovich, Coaster92, Coffee, Cohesion, Coldwatersupertramp, Colonies Chris, ConfuciusOrnis,Conversion script, Cosmic Latte, Costmary, Count Iblis, Courcelles, Crag, Cruising2hell, Crzer07, Csamschick, Curb Chain, Curps, Cxz111, CyberSeraph, Cyde, Cyrius, DGaw, DTMGO, DVDR W, Dacium, Dan, Dandylian, Daniel J. Leivick, Danny lost, Dante Alighieri, DarkMystik1, Darylgolden, Dasani, DaveChild, DaveRusin, David Cochrane, David Gerard, Davydog, Dawn Bard,Dayewalker, Dbachmann, DeadEyeArrow, Deathphoenix, Deckiller, Delhibm40m, Deor, Der zukünftige Führer von Amerika, DerHexer, Derek Ross, Dermod, Descendall, Deutschgirl,Dharmaruci, Diego Moya, Differentname, Digitalfestival, Dilcoe, Dimitrakopulos, Dino, Dinofant, Diptanshu.D, Discospinster, DiverDave, Dlc.usa, Doc Tropics, Doctor Girl, Dominus Vobisdu,Doniago, Donner60, DoomScythe, Doovinator, DougsTech, Dougweller, Doulos Christos, Dr.K., Dr.Siju, Drbreznjev, Dreadstar, Drmies, Dsp13, Dstanfor, Duncharris, EagerToddler39, Ebyabe,Echosthefall, Eclecticology, Ed g2s, Edison, Editor2020, Edwinhubbel, Eeekster, Eenu, Effer, Eggsyntax, Ekhalom, El C, ElTyrant, Elkman, Ellegirl, Ellenlongo, Ellywa, Eloquence, EoGuy,Eonechoes, Epbr123, Erebus Morgaine, Erekint, Erik Lönnrot, Eskild, Espoo, EthicsGradient, Everyking, Expertricky, Expertseries, Explicit, FKmailliW, Farhansher, Fastfission, Fastily,Favonian, Feezo, FeloniousMonk, Fengshuimasterwu, Finn-Zoltan, Flamewine, Flowerpotman, Flyer22, Foobaz, FormerIP, Foxj, Fractain, François Robere, Frater5, Fred Bauder, Fredrik,FreeKnowledgeCreator, FridayFourthMay2007, Frostlion, Frymaster, Frze, Fsolda, Fulcanelli, Func, Fuzzypeg, Fzvarun, G Rose, GENE RAY 33, GSlicer, Gaba p, Gadfium, Gaius Cornelius,GalaazV, Galoubet, Ganeshk, Gareth Owen, GarryP, Garryj145, Gary D, Gary PH, Garzo, Gatemansgc, Gerbrant, Gerfinch, Gilliam, Gillyweed, Givedarkkk, Glenn, GliderMaven, Gmaxwell,Goblin Prince, Gogo Dodo, Gokulayur, Goobergunch, Goustien, Grace suriel, GraemeL, Greenboite, Grfpopl, Griswaldo, Ground Zero, Grungey baby, Gråbergs Gråa Sång, Guanaco,Guillaume2303, Gurch, Gurukkal, Guyonthesubway, Gwendolynsutherland, Gwernol, Gzornenplatz, Hadal, HaeB, Haeinous, Haham hanuka, Haidam, Halfunits, Hamdello, Hans Adler,Hanuman Das, Harland1, Haruth, Hdt83, Headbomb, Heimstern, Hemanshu, Heron, Hersfold, HexaChord, Hgilbert, HiDrNick, HiLo48, Hipocrite, History by Christians, Horoworld,Horsechestnut, Hsriniva, Humus sapiens, Huxtopic, Hydrogen Iodide, Hyperdeath, INkubusse, Iamamm, Icez, Iching88, Ickydog, IdLoveOne, Ihcoyc, Indon, Indya1000, Inka 888, Intelligentqa,Intrigue, Island Dave, Islander(Scandinavia), Itsmejudith, Ixfd64, J.delanoy, JDPhD, JIP, JLaTondre, JRM, JSpung, Jackk Slattery, Jagged 85, James Chamberlan, JamesA, Jameserven,Jameshfisher, Jamesx12345, Jan Arkesteijn, Jarble, Jason Potter, Jbhunley, Jclerman, Jeandré du Toit, Jeendan, Jeepday, Jeff3000, Jefffire, Jeffq, Jembooth, Jethro the Bus Driver, Jgtl2,Jilethemile, Jim10701, Jim1138, JimVC3, Jimifloydrix, Jimmy5466, Jimokay, Jimp, Jitterro, Jivatmanx, Jj137, Jlakshminarayan, Joanjoc, John, John Charles Webb, John Vandenberg, John ofReading, JohnBump, Johnleemk, Johnny06man, JohnnyJr, Johnuniq, Jojit fb, Jokestress, Jonik, Jonnabuz, Jonnysonthespot, Jordan Rothstein, Jose77, Joshua Arent, JoshuaZ, Jossi, Jotomicron,Joy10, Joyous!, Jpgordon, Jrdioko, Jtm71, Julian Felsenburgh, Jusdafax, Jusjih, JvaGoddess, K.J.Grey, Kakarot 9517634, Kaltenmeyer, Kamlesh kam2003, Kaobear, Karanis, Kartikay1955,Kathleen.wright5, Ken McRitchie, Kenneth Cooke, Kerotan, Khazar2, King Vegita, KingHooves, Kingpin13, Kinst, Kitiwiskas, Klocek, Kmweber, Koavf, Kwamikagami, Kwertii, Kwork2, LKensington, LNchic, Lacatosias, Lacrimosus, Lalupamia, Landroo, Laoma, Latacash999, Lawilkin, Leasnam, Lee Daniel Crocker, Lenoxus, Leonid 2, Lewys, Lifebaka, Liftarn, Lightmouse,Ligulem, LikeLakers2, LilHelpa, Linkin park for gb, Littleolive oil, Logan, Lolx23lol, Loodog, Looxix, LordK, Lowellian, Ludwigs2, Lugia2453, Lumos3, Luna Santin, Lundse, LuzoGraal,MEKILOOLOO, MONGO, MSchmahl, Macadoods, Macalves, Macofe, Magicstuff99, Magioladitis, Majorly, MakeSense64, Man vyi, Mangoe, Mani1, Manisero399, Mann jess, Marcercam,Marianocecowski, Mark Arsten, Marshallsumter, Marskell, Martin Berka, MartinPoulter, Mashford, Masteryorlando, Matthead, Maunus, Maurice Carbonaro, Mauricelavenant, Mav,Maximaximax, Maximus Rex, MayoPaul5, McGeddon, McSly, Mccready, Mean as custard, MediaMangler, Meeples, Metropolitan90, Michael Devore, Michael Hardy, Midas touch, MikeRosoft, Miladt, Minerva20, MinorProphet, Mintguy, Mishabogic, Misodoctakleidist, Missvain, MisterTin, Mitaphane, Mkweise, Mmpant, Modemac, Modernist, Moeron, Momolee, Monedula,Moneya, Montrealais, Moreschi, Morgan Leigh, Moriori, Morningstar2651, Moshe Berlin, Mousomer, Mr Stephen, Mrspalmreader, Mssnlayam, Mstroeck, Mutt Lunker, Myrvin, Mystylplx,Mythealias, Nahums1, Naileshpatel, Naniwako, Nashhinton, Natascha1, Nathanael Bar-Aur L., NawlinWiki, NaySay, Nbb0ffice, Nealparr, Neckbrace, Neilc, Nerval, Neutrality,NewEnglandYankee, Nfr-Maat, NiceGuyEduardo, Niceguyedc, Nick Number, Nick-in-South-Africa, Night Gyr, Nihiltres, NikolaiLobachevsky, Ninewind, Ninly, Niteowlneils, Nixdorf,Noformation, Northern, Notary137, Novangelis, Novum, Nposs, Nsaa, NuclearWarfare, Nufy8, Nunh-huh, Nuzvid, O.Koslowski, Obsessivelanguagelearner, Ocaasi, Occult wizard, Odin 85thgen, Ohconfucius, Ohnoitsjamie, Old Moonraker, Old Watchman, OldManCoyote, Ollj, Omnipaedista, OpenMind, Optim, Orangemarlin, Orthotox, Ospix, Other Choices, Outlookc, OverlordQ,OwenX, Oxydo, P64, Pamri, Passargea, Patellokesh, Paul August, Paul Barlow, Paul Quigley, Paulmcdonald, Pavel Vozenilek, PebblesMeow, PedroPVZ, PelleSmith, PetaRZ, Petersburg,Peterstrempel, Petiatil, Petrus4, Pgallert, Pgk, Phasis, Phattanner007, Phil153, Philip Trueman, PhilipO, Philippe Ginouillac, Phillip J, Philosophus, Philwiki, PiCo, Piano non troppo, Pigman,Pinethicket, Pink!Teen, Piper Almanac, Pitchka, Pixiequix, Pjacobi, Pjvpjv, Pne, Poccil, Pol098, Polisher of Cobwebs, Polyamorph, Pomoblackbird, Poorsod, Porqin, Portillo, Prietoquilmes,Prosfilaes, Pseudomonas, Pseudothyrum, Pstanton, Psychicguild, Puchiko, QTxVi4bEMRbrNqOorWBV, Qazzx, Qualihost, Quangbao, Quantamflux, Quibik, Quuxplusone, Qxz, R'n'B, RK,RPGLand2000, RaVenX, Radon210, Raeky, Rafkha86, Ragesoss, Rajeshwaranand, Raju Veluthakkal, Ramayan, Rameshguru, Rampratapbishnoi, Random user 39849958, Random-chess,RandomCritic, RandomP, Rarehoarder, Rasmus Faber, RasputinJSvengali, Ray Dassen, RayTomes, Raymond arritt, Rbellin, Rdsmith4, Realtymatching, Recognizance, RedRabbit1983, Redvers,Reinis, Removedbelow, Resti, Revels4454, RexNL, Rfl, Rgbea, Rhobite, Rich Farmbrough, Rico402, Risingstar12, Rizzardi, Rjwilmsi, Rlinfinity, Rlongman, Rmisiak, Robert1947, Robertcurrey,RogoPD, Rohiniranjan, RossPatterson, Rothorpe, Rsokhi, Rtrrt, Rudrasharman, Rumbird, Rurik3, Rursus, Ruud Koot, Ryulong, Rzvas, S3000, SD5, SNIyer12, Saberlotus, Saedon, Sam Korn,Sam Vimes, Samir, Samsara, Samuel Grant, SamuelTheGhost, Santbetra, Sapphic, Sarranduin, Satellizer, Satori, Saturn1975, Sbmeirow, ScAvenger lv, Scarian, Scepticalidealist, Sceptre,SchreiberBike, SchuminWeb, SciFiApostle, Science Solider, Scientizzle, Seaj11, Searchingsachin, Searchme, Second Quantisation, Second Quantization, Self-ref, Sengupta6931, Senyor Nuclear,Seoss, Seraphimblade, Sethian, Sfacets, Sfan00 IMG, Sgerbic, Shadowjams, ShahJahan, Shan2014, Shanoman, Shantavira, SheffieldSteel, Shii, Shirik, Shlomi Hillel, Short Brigade HarvesterBoris, Shreevatsa, Shridharvk, Siddharth srinivasan, Sidewalkvendor, Siha, Silence, SimonWarcup, Sinhala Jyotishaya, Siteguru, Skizzik, Slartibartfast, Slatersteven, Slayer of Cliffracers, Sloane,Slowking Man, Smartallic2345, Smiloid, Snoyes, SocratesJedi, Sodium, Sohan113, Someone else, Someot, Sonett72, Sparree, Spazzm, SpeedyGonsales, SpookyMulder, Sptata, Squiddy,Squiquifox, StarHeart, StarLightPiazza, Starjack, StaticVision, Stephan Schulz, SteveBaker, Stevertigo, Storm Rider, Str1977, Suidafrikaan, SummitFreeze, Sun Creator, Sunrise, Sylent,Syncategoremata, TUF-KAT, Tannin, Tapir Terrific, Tayste, Tbhotch, Tdonelson, Teapeat, Techman224, TehShyster, Teklund, Terra angelica, Terrymacro, Texture, Tgeairn, Thaurisil, TheAnome, The Evil IP address, The Illusive Man, The elephant, The man 2000, The undertow, The www www, TheScotch, Theodore7, Thirdeye99, Thiselena, Thoross, Tide rolls, Timc, Timwi,TippyGoomba, Toby Douglass, Toccata quarta, Tom, Tom Lougheed, Tom Peters, Tom harrison, Tommy2010, Tony Sidaway, Toussaint, Tpbradbury, TracyRenee, Trappist the monk, Trivialist,Tryptofish, Tududu, Tunnels of Set, Twinsday, Two16, TyA, Tyco.skinner, TylerJarHead, Ufiuza, Uncle G, UnnaturalSelection, UnqstnableTruth, Urhixidur, Usability 3, UtDicitur, Vajay31,Valheed, Valluvan, Valravn, Vanisaac, Vanished User 0001, Vanished user kasjqwii3km4tkid, Vashikaran11, Vedicfolks, Verbal, Versageek, Veryscarymary, Victor Dorantes, Vilcxjo, Vina,VinceCarter32, Violetriga, Viriditas, Visakavel, Vishal4092832, Vivek.calvin, Vorpal blade, Vrenator, Vroman, Vsmith, Vssun, WLU, WP Editor 2011, WRK, Wahoofive, WalterJKin, Wanderapr, Warkos, Wassermann, Wayland, Wayne888, Wcs187, Wednesday Next, Werieth, Wetman, WhatProbablyKnow, WhatWasDone, Whiskey Rebellion, Widr, Wikiklrsc, Wikisy, Wikitrololo,Will Beback, Willbyr, William M. Connolley, Wiowio, Wipe, Wmahan, Wolfkeeper, Wolfrock, Wordup 10, WormRunner, WoweeeZoweee, Xanzzibar, Xaoiv, Xelgen, Xpaulk, Yagazuzy,Yahia.barie, Yamaguchi先 生, Yamamoto Ichiro, Yintan, Yk Yk Yk, Yngwin, Yobol, Yworo, Yzalzy, Zach bender, Zachariel, Zandperl, Zedshort, Zendonut, Zero1328, Zeusnoos, Zoso,Zundark, Zuytdorp Survivor, Zymurgy, 1819 anonymous edits

Astronomy  Source: http://en.wikipedia.org/w/index.php?oldid=621004770  Contributors: -- April, 100110100, 1297, 137.205.8.xxx, 158.152.145.xxx, 1exec1, 1narendran, 216.30.135.xxx, 217.98.151.xxx, 24.12.65.xxx, 24.26.194.xxx, 28421u2232nfenfcenc, 321bubbles, 331dot, 3Nigma, 4.46.3.xxx, 65.10.163.xxx, A brisson, A.Ou, APH, ASDF, AVand, Acidtripping, Acroterion, AdAdAdAd, AdamW, Adamw, AdjustShift, AdultSwim, Ageekgal, Ahoerstemeier, Aj g''qe, Akamad, Al Sheehan, Alanchen3311, Alansohn, Alanyst, Aldaron, Aldie, Ale jrb, Aleenf1, Alexius08, Alfio, Ali, All Is One, Allen 6666, AllenWayneMao, Altenmann, Anastronomer, Andre Engels, AndrewWTaylor, Andrewman327, Andromeda321, Androstachys, André Oliva, Andy, Andycjp, Andyjsmith, AngelOfSadness, Angela, Angr, Anmclarke, Anna Lincoln, Anonymous editor, Antandrus, Anthony Arrigo, Anticent, Antiracia, Aowpr, Ap William, Aphaia, Apptas, Arbeiter, ArglebargleIV, Ark, Arkham, Arkuat, Arlen22, ArmadilloProcess, Armchair info guy, Arpingstone, Art LaPella, Artegis, Artichoke-Boy, Ashill, AstroMalasorte, AstroNomer, Astrocog, Astronautics, Athenean, Attilio74, AubreyEllenShomo, Aulis Eskola, Authenticmaya, Aviatormd, Avoided, Awolf002, AxelBoldt, Ayman, BRG, Bad Astronomer, Banno, Barek, Bart133, Batmansuper, Bcjordan, Bcorr, Bebenko, Beetstra, Beland, Belovedfreak, Benmacdonald22, Bfigura's puppy, Bfong2828, BiT, Bihco, Bilbo571, Bill Thayer, Billywise01, Binabik80, BlGene, Blatant copyright infringement), Bliduta, Blue520, Bluee Mountain, Bluemoose, Bluesquareapple, BlytheG, Bmicomp, Bmorton3, Bob facal, Bob615615, BobQQ, Bobblehead, Bobblewik, Bobo192, Bobtbuilder, Bongwarrior, Boobmilk22, Bootyy, BorgQueen, Borislav, Bow bowl, Bradeos Graphon, Branddobbe, Brandmeister, Bren josh was here, Brian Crawford, Brian0918, Brianga, Brion VIBBER, Briséis, Brockert, Bronger, Brougham96, Brunton, Bryan Derksen, Bsadowski1, Bull1, Bulwersator, Bunchofgrapes, Bunny-chan, Burner0718, Bynhola, C.Fred, CWY2190, CYD, Cadiomals, Caiaffa, Caltas, Camembert, Canderson7, Capricorn42, Captiveaire, CardinalDan, CarnMeynen, Casull, Causa sui, Celery2011, Cenarium, Cgs, Charvest, Chas zzz brown, Chenyu, Chicago god, Chillum, Chris Brennan, Chris.nelson112, ChrisO, Christian List, ChristopherWillis, Chromastone1998, Chun-hian, Cieloscuro, Civil Engineer III, Ckatz, Closedmouth, Cmdrjameson, Cobi, Cocu, Codex Sinaiticus, Coffee, Cometstyles, Comic, Coneslayer, Confettimonster, Conversion script, Coupie06, Crecy99, Cremepuff222,

Article Sources and Contributors 35

Crusadeonilliteracy, Csji, Cuddlyopedia, Cula, Cureden, Curps, Cybercobra, Czeror, DBishop1984, DJ Clayworth, DVdm, Daatass, Dabomb87, Dak, Dandrake, Danger, Daniellecoley88,DarkHorizon, Darpad, DarthSwim, DavidLeighEllis, DavidLevinson, Davodd, Dda1996a, Debresser, Deepanjan nag, Deglr6328, Deiaemeth, Delta x, Deor, DerHexer, Desiphral, Deuar, Dfred,Dgw, Dhriti pati sarkar 1641981, Diaryarden, Diggity-diggity-doom, Dinogamer04, Dinohunter, Dinosaur puppy, Discospinster, Dissimul, DixiePixie, Djaquay, Dna-webmaster, Doctorheinweth, Dolphonia, Dookiefart, Dorftrottel, Doulos Christos, Dourbest, Download, Dozols, Dpeters11, Dpr, Dr. Straw ina bird123, Dr. Submillimeter, Dracontes, Dragon Dave, DreamHaze,Drift chambers, Drmies, Drumbeatsofeden, Dskluz, Dsulliv, DubaiTerminator, Duncharris, Dysprosia, EVula, Ealdgyth, Earthsky, Edderso, Edward, El C, Eleassar, EliasAlucard, Ember of Light,Emil233, Enceladus, Enok Walker, Enviroboy, Epbr123, Erernityram, Eric Forste, Ericd909, EscapingLife, Eurotopia, Evercat, Everyking, Evyn, Ewulp, Excirial, Extra999, FF2010, Fabiform,Falcorian, Fcn, Feezo, Femto, Fern 24, Fir0002, Fito, Fjörgynn, Flauto Dolce, Flayreis, Flehmen, Flowerpotman, Floydian, Flyguy649, Fonzy, Fotaun, Fountains of Bryn Mawr, FrancoGG,Frankie0607, Fredbauder, FreddieStar*, Fredrik, Friginator, Fsdajgkjkjbjvsafkjkslafjk, Fsgregs, Full Shunyata, Fuller1534, Funnyfarmofdoom, Funnyfred2912, Fuzheado, Fuzzie, Fvw, G.Campbell, G8ina, Gadfium, Gail, Galoubet, Gandalf61, Ganeshk, Gap9551, Gareth Owen, Gego, Gene Nygaard, General Epitaph, Gentgeen, Geoff Plourde, Geologist258, Geremia, Ghyll,Giftlite, Gig9876, Gilliam, Gimboid13, Gimmetrow, Gioto, Gleet, Glen, Go for it!, Gogo Dodo, Good.logos, Graffittibob, Graham87, Grahamching, Grand thief olarn, Gravitan, Great EscapeHero, Greengreengreenred, GregorB, Grenavitar, Greyhood, Grunt, Guanaco, Gummy bear14, Guppy, Gurch, GuyDFaber, Gwernol, Hadal, Half65, Hanberke, Hanumanman, Harp, Hasek is thebest, Haukurth, Hawaiiboy, Haza-w, Hdt83, Headbomb, Hello71, Hemanshu, Heracles31, Herakles01, Heron, Hhaarty, Hmrox, Hovik, Husond, II MusLiM HyBRiD II, IMAHORSEY,Iambeast789, IanOsgood, Icairns, IceUnshattered, Iceblock, Icey, IdLoveOne, Idiots1212, Igiffin, Iikkoollpp, Ijustateyou, Ikpleo, Indon, Intelligentsium, Iridescent, Isam, Island, Italia2006, Ivovan der Horst, Ixfd64, Izogi, J.delanoy, JForget, JFreeman, JHouklis, JHunterJ, JIMBO WALES, Jac16888, Jack of ages, Jackol, Jagged 85, James P Twomey, Jameswillis, Janke, Javert,Javierito92, Jay, Jazzer93, Jdhowens90, Jeendan, Jeepday, Jeffmedkeff, Jeffparisi, Jengirl1988, Jerryb1961, Jespley, JesseGarrett, Jhaase, Jhonyl38, Jiddisch, Jimmy5466, Jinlye, Jklin, Jkominek,Jmencisom, Jmh649, Jmulek, Jmwolfe, Joborrett, Joelster, John, John254, JohnOwens, Johnman239, Johnuniq, JonathanD, Jonverve, Jorgenev, JorisvS, Jose77, Jossi, Jotuns, Joymmart, Joyous!,Jpreston453, Julia W, Junglecat, Juniordrumkit, Jusdafax, Jusjih, Justin Eiler, Jwissick, JzG, K, 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Image Sources, Licenses and Contributors 36

Image Sources, Licenses and ContributorsFile:Venice ast sm.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Venice_ast_sm.jpg  License: Creative Commons Zero  Contributors: User:ZacharielFile:Astrologia-tynkä.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Astrologia-tynkä.jpg  License: Public Domain  Contributors: Hautala, Theoteryi, Waldir, WolfgangRiegerFile:Marcantonio Raimondi - Two Women with the Signs of Libra and Scorpio.jpg  Source:http://en.wikipedia.org/w/index.php?title=File:Marcantonio_Raimondi_-_Two_Women_with_the_Signs_of_Libra_and_Scorpio.jpg  License: Public Domain  Contributors: Cirt, Lalupa, PostdlfFile:Cicero - Musei Capitolini.JPG  Source: http://en.wikipedia.org/w/index.php?title=File:Cicero_-_Musei_Capitolini.JPG  License: Creative Commons Attribution-Sharealike 3.0,2.5,2.0,1.0 Contributors: Glauco92File:Quadritpartitum.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Quadritpartitum.jpg  License: Public Domain  Contributors: Lx 121, ZacharielFile:Translation of Albumasar Venice 1515 De Magnis Coniunctionibus.jpg  Source:http://en.wikipedia.org/w/index.php?title=File:Translation_of_Albumasar_Venice_1515_De_Magnis_Coniunctionibus.jpg  License: Public Domain  Contributors: PHGCOMFile:Meister von San Vitale in Ravenna 004.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Meister_von_San_Vitale_in_Ravenna_004.jpg  License: unknown  Contributors: -File:Isidor von Sevilla.jpeg  Source: http://en.wikipedia.org/w/index.php?title=File:Isidor_von_Sevilla.jpeg  License: Public Domain  Contributors: AndreasPraefcke, Anual, Dionisio,Ecummenic, Enrique Cordero, Evrik, Ixtzib, JMCC1, Ketamino, Kokodyl, Mattes, Schaengel89, Sebastian Wallroth, SvencbFile:Robert Fludd's An Astrologer Casting a Horoscope 1617.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Robert_Fludd's_An_Astrologer_Casting_a_Horoscope_1617.jpg License: Public Domain  Contributors: Chiswick ChapFile:Brooklyn Museum - Page from an Astrological Treatise.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Brooklyn_Museum_-_Page_from_an_Astrological_Treatise.jpg License: Public Domain  Contributors: AnRo0002, NeverDoING, Romaine, TúrelioFile:Karl Popper.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Karl_Popper.jpg  License: unknown  Contributors: LSE libraryFile:Gnome-mime-sound-openclipart.svg  Source: http://en.wikipedia.org/w/index.php?title=File:Gnome-mime-sound-openclipart.svg  License: unknown  Contributors: User:EubulidesFile:Bdrates of Japan since 1950.svg  Source: http://en.wikipedia.org/w/index.php?title=File:Bdrates_of_Japan_since_1950.svg  License: Public Domain  Contributors: DemmoFile:Woman in the Moon.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Woman_in_the_Moon.jpg  License: Public Domain  Contributors: John LylyFile:LH 95.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:LH_95.jpg  License: Public domain  Contributors: NASA, ESA, and the Hubble Heritage Team(STScI/AURA)-ESA/Hubble CollaborationFile:Crab Nebula.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Crab_Nebula.jpg  License: Public domain  Contributors: NASA, ESA, J. Hester and A. Loll (Arizona StateUniversity)File:SLNSW 479519 16 Observatory SH 198.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:SLNSW_479519_16_Observatory_SH_198.jpg  License: Public Domain  Contributors:99of9, MattinbgnFile:Planisphæri cœleste.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Planisphæri_cœleste.jpg  License: Public Domain  Contributors: Geagea, Jan Arkesteijn, Jay2332, Joopr,Leyo, STyx, W!B:, 2 anonymous editsFile:AiKhanoumSunDial.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:AiKhanoumSunDial.jpg  License: Creative Commons Attribution-ShareAlike 3.0 Unported  Contributors:Green fr, Ismoon, JuergenG, Kilom691, Sailko, Soerfm, TcfkaPanairjdde, World ImagingFile:Galileo moon phases.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Galileo_moon_phases.jpg  License: Public Domain  Contributors: GalileoFile:USA.NM.VeryLargeArray.02.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:USA.NM.VeryLargeArray.02.jpg  License: GNU General Public License  Contributors:user:HajorFile:In Search of Space.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:In_Search_of_Space.jpg  License: unknown  Contributors: JmencisomFile:The Keck Subaru and Infrared obervatories.JPG  Source: http://en.wikipedia.org/w/index.php?title=File:The_Keck_Subaru_and_Infrared_obervatories.JPG  License: Creative CommonsAttribution-ShareAlike 3.0 Unported  Contributors: SasquatchFile:Wpdms physics proton proton chain 1.svg  Source: http://en.wikipedia.org/w/index.php?title=File:Wpdms_physics_proton_proton_chain_1.svg  License: Public Domain  Contributors: seebelowFile:Uvsun trace big.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Uvsun_trace_big.jpg  License: Public Domain  Contributors: (supposed to be NASA due to this rather similarimage; see e.g. File:PIA03150.png; thus the material will be under the well known PD licensing terms)File:Observatórium Lomnický štít 1.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Observatórium_Lomnický_štít_1.jpg  License: Creative Commons Attribution-Sharealike 3.0 Contributors: User:BubamaraFile:dust.devil.mars.arp.750pix.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Dust.devil.mars.arp.750pix.jpg  License: Public Domain  Contributors: Bdamokos, Ruslik0,Saperaud, Scanmap, TheDJFile:Ant Nebula.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Ant_Nebula.jpg  License: Public Domain  Contributors: NASA, ESA & the Hubble Heritage Team (STScI/AURA).Acknowledgment: R. Sahai (Jet Propulsion Lab), B. Balick (University of WashingtonFile:Milky Way Spiral Arm.svg  Source: http://en.wikipedia.org/w/index.php?title=File:Milky_Way_Spiral_Arm.svg  License: GNU Free Documentation License  Contributors: User:SurachitFile:grav.lens1.arp.750pix.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Grav.lens1.arp.750pix.jpg  License: Public domain  Contributors: STScl/NASAFile:Hubble Extreme Deep Field (full resolution).png  Source: http://en.wikipedia.org/w/index.php?title=File:Hubble_Extreme_Deep_Field_(full_resolution).png  License: Public Domain Contributors: NASA; ESA; G. Illingworth, D. Magee, and P. Oesch, University of California, Santa Cruz; R. Bouwens, Leiden University; and the HUDF09 TeamFile:Telescope trailer 22.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Telescope_trailer_22.jpg  License: GNU Free Documentation License  Contributors: Halfblue

License 37

LicenseCreative Commons Attribution-Share Alike 3.0//creativecommons.org/licenses/by-sa/3.0/