Astronomy: A HistoryAstronomy: A History

Early AstronomyEarly AstronomyAstronomy the oldest of the natural Astronomy the oldest of the natural

sciences.sciences.Early Early culturescultures identified celestial objects identified celestial objects

with with godsgods and and spiritsspirits. They related these . They related these objects (and their movements) to objects (and their movements) to phenomena such as phenomena such as rainrain, , droughtdrought, , seasonsseasons, and , and tidestides

Astrological TimeAstrological Time CalendarsCalendars of the world have usually been set by of the world have usually been set by

the Sun and Moon (measuring the the Sun and Moon (measuring the dayday, , monthmonth and and yearyear), and were of importance to ), and were of importance to agriculturalagricultural societies.societies.

The most common The most common modern calendarmodern calendar is based on is based on the the Roman calendarRoman calendar, which divided the year into , which divided the year into twelve months of alternating thirty and thirty-one twelve months of alternating thirty and thirty-one days apiece. days apiece.

In In 46 BC46 BC Julius CaesarJulius Caesar instigated instigated calendar reformcalendar reform and adopted a calendar based and adopted a calendar based upon the upon the 365 1/4 day year length365 1/4 day year length..

MesopotamiaMesopotamiaThe origins of The origins of WesternWestern astronomy can be astronomy can be

found in found in MesopotamiaMesopotamia, the "land between , the "land between the rivers."the rivers."

A form of writing known as A form of writing known as cuneiformcuneiform emerged among the Sumerians around emerged among the Sumerians around 3500-3000 BC that helped to document 3500-3000 BC that helped to document this information. this information.

EgyptEgypt It has been shown the Pyramids were It has been shown the Pyramids were

aligned towards the aligned towards the pole starpole star..When living in Alexandria, Egypt, Claudius When living in Alexandria, Egypt, Claudius

Ptolemy proposed that planets moved in Ptolemy proposed that planets moved in little circles that moved in bigger circles little circles that moved in bigger circles about the earth.about the earth.

For almost 1400 years people believed For almost 1400 years people believed this to be true. this to be true.

GreeceGreece The The Ancient GreeksAncient Greeks developed astronomy, developed astronomy,

which they treated as a branch of mathematics, which they treated as a branch of mathematics, to a highly sophisticated level. to a highly sophisticated level.

The first geometrical, three-dimensional models The first geometrical, three-dimensional models to explain the apparent motion of the planets to explain the apparent motion of the planets were developed in the were developed in the 4th century BC4th century BC. .

Their younger contemporary Their younger contemporary HeraclidesHeraclides PonticusPonticus proposed that the Earth rotates around proposed that the Earth rotates around its axis.its axis.

ChinaChinaAstronomy in China has a long history. Astronomy in China has a long history.

Detailed records of astronomical Detailed records of astronomical observations were kept from about the 6th observations were kept from about the 6th century BC, until the introduction of century BC, until the introduction of Western astronomy and the telescope in Western astronomy and the telescope in the 17th century. the 17th century.

Chinese astronomers were able to Chinese astronomers were able to precisely predict precisely predict cometscomets and eclipses. and eclipses.

IslamIslamThe Arabic world under The Arabic world under IslamIslam had become had become

highly cultured, and many important works highly cultured, and many important works of knowledge from of knowledge from Greek astronomyGreek astronomy and and Indian astronomyIndian astronomy were translated into were translated into Arabic, used and stored in libraries Arabic, used and stored in libraries throughout the area. throughout the area.

Western European Middle AgesWestern European Middle AgesThere was a lack of progress has led There was a lack of progress has led

some astronomers to assert that nothing some astronomers to assert that nothing happened in Western European happened in Western European astronomy during the Middle Ages.astronomy during the Middle Ages.

Copernican RevolutionCopernican RevolutionThe The renaissancerenaissance came to astronomy with came to astronomy with

the work of the work of NicolausNicolaus Copernicus Copernicus, who , who proposed a proposed a heliocentricheliocentric system. system.

His work was later defended, expanded His work was later defended, expanded upon and modified by upon and modified by Galileo Galileo GalileiGalilei and and Johannes Johannes KeplerKepler..

Heliocentric:Heliocentric: In which the planets revolved around the In which the planets revolved around the

Sun and not the Earth. Sun and not the Earth.

GalileoGalileoGalileo was among the first to use a Galileo was among the first to use a

telescopetelescope to observe the sky, and after to observe the sky, and after constructing a refractor telescope he constructing a refractor telescope he discovered the four largest moons of discovered the four largest moons of Jupiter in 1610. Jupiter in 1610.

This was the first observation of satellites This was the first observation of satellites orbiting another planet. orbiting another planet.

He also found that our Moon had craters He also found that our Moon had craters and observed (and correctly explained) and observed (and correctly explained) sunspots.sunspots.

Modern AstronomyModern Astronomy