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History of the Universe Notes

History of the Universe Notes. How big is the Universe?. There are more stars in the universe than grains of sand on earth.

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History of the Universe Notes

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  1. History of the Universe Notes

  2. How big is the Universe? • There are more stars in the universe than grains of sand on earth. • The light we receive from distant objects took over 4 billion years traveling 300,000,000 meters per second to reach earth. We are actually seeing what the objects looked like 4 billion years ago, before there was any life on earth • We do not know how big the universe is, or if it is infinite!

  3. How big is the Universe?

  4. How did the Universe Begin? • In the early 1920’s Edwin Hubble discovered that light given off by galaxies (spectra) shifted towards the red end of the electromagnetic spectrum. • This meant that the galaxies were moving away from the earth.

  5. How did the Universe Begin? • Hubble’s Law-By examining the amount of red shift Hubble was able to determine the speed at which galaxies were moving away from earth. Hubble found the most distant galaxies were moving away from earth the fastest. • This discovery led Hubble and other scientists to determine that the universe was expanding, which gave way to the Big Bang Theory.

  6. How did the Universe Begin? • According to the Big Bang Theory, all matter and energy in the universe was compressed into an extremely small volume that 13-15 billion years ago exploded and began expanding in all directions

  7. How did the Universe Begin? • Cosmic background radiation is radiation that is uniformly detected with radio telescopes from every direction in space; considered to be a remnant of the big bang.

  8. How did the Universe Begin? • Since anything with mass has gravity, as the universe expanded, some of the matter gathered in clumps and evolved into galaxies.

  9. Star formation Nebula Stars are born in clouds of stellar dust called nebula Nebula consist of mostly hydrogen, smaller amounts of helium, and trace amounts of larger elements

  10. Star formation Gravity Gravitational attraction depends on BOTH size and distance objects are apart Gravity condenses matter & increases temperature until … 10 million degrees (⁰C) is reached and fusion can begin

  11. Star formation Fusion Fusion is the process by which light nuclei (atoms) fuse together to make heavier nuclei (atoms) • Most commonly occurs with hydrogen and produces helium • Releases a HUGE amount of energy (which fuels more reactions)

  12. Star formation Fusion Proton H Neutron RxN Positron Neutrino 2H H 3He RxN H H Gamma Rays RxN 4He H Gamma Rays H H RxN 3He RxN 2H H http://www.astronomynotes.com/starsun/s3.htm

  13. Star formation Fusion So, six (6) hydrogen atoms are required to produce one (1) helium atom. • Helium to Carbon requires even greater temperatures, perhaps 1 billion K This, quite literally, is the fuel of the stars (and our sun) Once fusion begins, stars can take one of several life paths, ending with a bang, or a fizzle …….. (more coming later)

  14. Galaxy formation Again, gravity So, as mentioned above, everything with mass has gravity, and that is especially true for stars. - When many stars are attracted together due to gravity a galaxy is formed. Most galaxies (likely) formed shortly after the Big Bang when massive nebulae collapsed and began producing stars.

  15. Galaxy formation Galaxy collisions Because galaxies are moving (remember the red shift & Hubble & raisin bread mentioned above) collisions among galaxies are also thought to have played an important role in present day galaxies Galaxies come in several shapes, often influenced by collisions, including spiral (Milky Way), elliptical, barred spiral, and irregular shaped galaxies.

  16. Galaxy formation Spiral galaxy

  17. Galaxy formation Barred spiral galaxy

  18. Galaxy formation Elliptical galaxy

  19. Galaxy formation Galaxy size & # Galaxies are almost inconceivably large – • The Milky Way (our galaxy) is 100,000 light years across and contains around 200 billion stars. • Our closest galactic neighbors – the Large and Small Magellanic Clouds are 170,000 light years away from us. • 30 other galaxies exist within 5 million light years • According to NASA and the Hubble telescope, there are hundreds of billions of galaxies.

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