Unit Earth in Space.Topic 1: The Night Sky.

Vocabulary Terms to know for the Regents:

Horizon, altitude, coordinate system, constellation, zenith,

Polaris, ecliptic, lightyear

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• A. Mapping the Sky• As with any mapping, it is essential to make a

grid or coordinate system that uses an 'x' and 'y' axis to locate positions.

• For space, astronomers use a few different terms for each axis. All the points are measured in units of space called degrees. Degrees are broken into 60 minutes which are each broken into 60 seconds

• This has nothing to do with TIME!!!•

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From anywhere on earth (and in Astronomy magazine), coordinate points have these names:

Up Across From the celestial equator: (the extension of the earth's equator into space)

From the point at which the sun crosses the celestial equator during the spring equinox:

The 'y' axis point is called declination

The 'x' axis point is called the right ascension or hour circle

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Terms we use when viewing from home:Up Across

From any point on your horizon, looking up into the sky:

Starting with due North as 0º, East is 90º, South is 180º and West is 270º: back to north at 360

The 'y' axis point is called the altitude

The 'x' axis point is called the azimuth

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• Example: if you were looking at Scorpio and so was someone in Liberia, you would use the same declination and right ascension to describe the locations. (just like using Latin to name living things). These measurements would be the same no matter what day or time you looked at it!!!!

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• However, if you wanted to tell me where Scorpio was, looking from your backyard, you would measure its height above the horizon (altitude) and use a compass to tell me how far from due North it was (azimuth). These are only good from your house at the exact hour and day you took the measurements!!!

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• B: Things to See:• Using a star chart, find:• the ecliptic (line the sun seems to follow

through the stars during the year)• the zenith (point directly over an observer)• Polaris (the North Star: notice it is always in

the northern sky, at the exact same position, all the time!!)

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• Find the Ursa Major constellation, which contains the Big Dipper

• Learn to find Polaris by using the Big Dipper's 'pointer stars'

• The sky is divided into 88 sections called constellations, and stars in these sections are used to make pictures in the sky.

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• All of the stars you are looking at are many lightyears (the distance light travels in a year, which is trillions of miles) away.

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Topic 2: The Origin of the Universe:

• Vocabulary to know for the Regents:• Universe, stars, fusion, galaxies, Milky

Way Galaxy, local cluster, cosmic background radiation, spectrum, spectroscope, electromagnetic radiation, red-shift, Doppler Effect

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Astronomy Notes: Deep SpaceHubble overview:

http://hubblesite.org/explore_astronomy and Journey to a Black Hole:

http://hubblesite.org/explore_astronomy/black_holes/home.html

and then http://amazing-space.stsci.edu/resources/explorations to

do the following: planet impact, mission mastermind, Hubble Deep Field Academy, Telescopes from the Ground

up, Galaxies from the Ground Up, and No Escape: The truth about black holes

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A. The Universe:• 1. Universe is all known matter and

energy.• Age: est. 13.7 billion years old

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• 2. The Big Bang• 13.7 billion years ago, the Universe

began in a moment of time in which energy began to be changed into matter. (That's basically what E=mc2 means).

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3. Formation: The Big Bang Theory

• In the beginning was….???? Sphere of energy???? Time and space did not exist

• the energy became unstable and exploded….

• energy cooled over the first million years, and subatomic matter formed

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• Over time, electrons, protons and neutrons formed. As these slowed down a little,

• atoms of Hydrogen began to form. In time, gases coalesced to form stars, which are spheres capable of fusion (making heavier atoms from lighter atoms at millions of degrees).

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4. Galaxies

• . Many pockets of gas became galaxies of billions of stars moving together through space. Galaxies grouped together to form clusters of galaxies.

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Our galaxy is the Milky Way Galaxy, a spiral galaxy 100,000 ly across and 10,000

ly high. 200 billion stars.

• From http://www.astrodigital.org/astronomy/milkywaygalaxy.html A side view:

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And the overview:

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• . Ours is one of 22 galaxies in our local cluster. The nearest spiral galaxy to us is the Andromeda Galaxy.

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B: Measuring Our Universe• 1. Ever since that first initial violent

explosion, our universe has continued to expand.

• How do we know? We watch all types of stars, nebula, galaxies, quasars, pulsars, and black holes.

• Most importantly, astronomers discovered cosmic background radiation that seems to be great energy left over from a terrific explosion.

http://www.classzone.com/books/earth_science/terc/navigation/chapter28.cfm http://csep10.phys.utk.edu/astr162/lect/cosmology/cbr.html 20

• 2. Evidence of an expanding universe: –Doppler Effect: most galaxies

show red shift :–farthest galaxies show most shift

• http://www.classzone.com/books/earth_science/terc/navigation/chapter28.cfm

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3. Electromagnetic Energy (EME)

• All matter gives off electromagnetic radiation (including you?), which is measured in wavelengths and frequencies of both visible and invisible light. See page 14 of ESRTand lab 8-7.

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• These wavelengths make up the spectrum. Each substance gives off its own spectra when viewed through a spectroscope. (We'll do this using charts and in lab).

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4. Doppler Shift

• When an object moves away at great speeds, its spectra shifts to longer wavelengths (red-shift) and

• when it is moving towards us its spectra shifts to shorter wavelengths (blue-shift).

• The faster it is moving, the greater the shift will be. This is called the Doppler Effect.

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• When we look at stars, we are looking backwards in time. The farthest quasars (very old stars) are 13.7 billion ly away.

• Present predictions are for the universe to continue to move outward forever. Too bizarre!

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Topic 3: Stars

• The matter in the universe separated in all directions.

• 80-90% of the mass of the universe is invisible dark matter and dark energy. None of our instruments can detect them, but we know they must be there due to the laws of gravity!!

• Most matter is in the form of stars or star dust. (You and I are star dust!!)

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• A. Stars are spheres capable of thermonuclear fusion: (creating new elements by smashing smaller elements together.)

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B. Classification of stars• 1. On the H-R diagram, stars are

classified according to their size, temperature and luminosity (how bright the star REALLY is).

• H-R Diagram: Temperature vs. luminosity chart.

• Page 15 of ESRT: shows 4 main classes of stars.

•• http://casswww.ucsd.edu/public/tutorial/HR.html

• http://www.astro.ubc.ca/~scharein/a311/Sim/hr/HRdiagram.html

• See page 15 of ESRT , text p. 626 and lab 8-8 for classifications.

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• 2. Star Temperature and color: • Hot stars are blue, cool stars are

red• 3. Star Luminosity (absolute

magnitude): star’s TRUE brightness compared to the sun: big stars are bright, dwarf stars are dim.

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• 4. Composition of the star: what elements are in the star and in its atmosphere.

• 5. Spectra tells us that, because each element has its own spectral fingerprint.

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• C. Life Cycle: • Protostar (from nebula)• Main sequence (stable)• Uses up hydrogen, expands and cools• Either novas or supernovas• Becomes either white dwarf, neutron

star or black hole, depending on how much mass it had.

• http://www.classzone.com/books/earth_science/terc/navigation/chapter28.cfm

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• 1.All stars begin as protostars when space dust has formed a sphere that becomes very hot, leading to fusion: when hydrogen is turned into helium in its core.

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• 2.The Main Sequence Stars are stars that are stable and have a lot of hydrogen left in their cores.

• These include:

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• Blue Supergiants: massive stars that only exist millions of years before they

• Expand to become cooler Red Supergiants

• That will blow up (supernova), creating nebula (large clouds of star dust) and either neutron stars or black holes. Large stars create helium, lithium…..iron.

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• Stars like our star, the Sun, are typical main sequence stars. –It is not very large or hot.–When it becomes old (uses up its

hydrogen) it will expand and become a Red Giant.

• http://sohowww.nascom.nasa.gov

• Age: 4.6 billion years old• Red Giant stage in 5 billion years.• It will nova and become a white dwarf.

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• Red Dwarf stars are very small and cold, and use up their fuel slowly.

• they ‘live’ for many billions of years before becoming brown dwarf stars….

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3. After the Main Sequence

• The Red Supergiants are the second stage in a blue supergiant’s ‘life cycle’. These supernova and leave black holes and neutron stars.

• White and Brown Dwarf Stars are the remnants of exploded Red Giants.

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• Heavy elements are formed during these massive explosions and interactions.

• The matter in the universe is constantly recycled into new dust and stars and energy. Nothing has been added or taken away (according to the laws of Physics) since the initial Big Bang.

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Topic 4. Measuring Distances and Energy in Space:

• A.Lightyear is the distance light travels in a year.

• Speed of light: 186, 000 miles/second – (670, 000, 000 miles/hr)

• Lightyear : 10 trillion km, (or about 6 trillion miles )

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• B. A Parsec is 3.26 lightyears.• The distance to the star nearest

earth is 4.2 lightyears or 1.3 parsecs.• It is a parallax measure of one arc-

second of space.

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C. Electromagnetic Spectrum:

• 1. energy given off in transverse waves.

• P. 14 ESRT

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• 2. All EME travels at the speed of light.• Longer wavelengths = lower energy have

low frequency• Shorter wavelengths = more energy• have higher frequency

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• 3. Our star (sun) gives off primarily visible light has a continuous spectrum of VISIBLE LIGHT

• Sun also gives off UV, infrared, and other wavelengths

•

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D. Constellations:

• Stars that SEEM to be close together. People see an ‘image’ and make up stories

• 88 recognized constellations (includes picture and space around/behind it)

• (Measured in Right Ascension and Declination from ecliptic)

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•Circumpolar constellations: p. 617 text and link to animation http://www.astronomy.ohio-state.edu/~pogge/Ast161/Movies/#circum

• Big Dipper: p. 617 text• Seasonal Constellations: p. 618-619 text and p. 714-715

text

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