Astronomy Overview PowerPoint Notes

Astronomy Overview

Big Bang

  •  Beginning of our Universe (~15-17 bya)
  •  Evidence: Quasars + Doppler Effect

Galaxies

  •  Milky Way is our galaxy & is a spiral
  •  Milky Way is ~100,000 light years across
  •  Our Sun is located ~2/3 way out, in one of its spiral arms
  •  Andromeda is our sister galaxy
  •  We are part of M17--the Local Group

3 main types--spiral, ellipKcal & irregular

Nebular Theory

Formation of our solar system ~4.6-4.8 bya

Evidence:
Craters on planets throughout the solar system

Age of rocks on Earth & Moon

Our Solar System....

  •  99% of the nebula became the sun.
  •  0.8% became Jupiter
  •  The other 0.2% became the other planets

 The primary atmosphere of inner planets was blown off when nuclear fusion first occurred--when the Suns core hit 10,000,000° C

Hydrogen Fusion

  •  Remember:
  •  4H 1He
  •  Gives off radiant energy in the form of the electromagnetic spectrum

 (Called nuclear fusion!)

Earths Atmosphere Over Time

  •  Visible light, infrared & UV light impact life on Earth

 This gives Earth a greenhouse effect in which life can flourish 
 Billions of years ago bacteria mutated into photosynthesizing cyanobacteria which pollutedenvironment with O2

Earths Atmosphere (cont.)

The increase in O2 in the atmosphere has changed the atmosphere over time
~1.5 billion years ago the Earth had the current levels of N2 and O2

Asteroid Impacts & Mass Extinctions

  •  Mass extinction happens at the end of the Paleozoic (~250 mya) ~90% extinct
  •  Mass extinction happens at the end of the Mesozoic (~65 mya) ~65% extinct
  •  These were due to meteorite impacts
  •  Food chain breaks down due to slow down of photosynthesis (nuclear winter)
© lbranch 2013