Earth - an island in space
Solar System
Sun and nine planets
Galaxies
Groups of stars
The Universe
When and How did it all form????
Origin of the Universe
The Big Bang
=> 14-20 billion years ago the universe began during a cataclysmic
release of energy from a point source of infinite mass.
- 10-43second -> matter/antimatter
- quark soup - inflation
- 3000 bill degrees K - hadrons
- 3 minutes - dueterium & He nucleii
- 300k - H & He - photons released = light
- first galaxies (~ 1 bill. Yrs.)
- continued expansion
What is the evidence for this?
An Expanding Universe
Cosmic Background Radiation
How do we know the universe is expanding?
Expansion is suggested by the Red Shift (Hubble, 1929)
Red shift can be explained by the Doppler Effect
Evolution of Stars - Element Factories
Stars begin as clouds of dust & gas = Nebula
Gravity -- protostar
High pressure and temperatures
H atoms fuse together to form He = fusion
As stars run out of fuel
Become larger & explode
Supernova -> forms another nebula
Begins to create heavier elements
He - C - N - O, ect.
Origin of the Solar System => Nebular Hypothesis
a) ~5 bill. yrs. ago - solar system began as large, slowly
rotating cloud of dust and gas - Solar Nebula
=> material from a supernova
b) Cooling and Gravity => from cloud to sphere.
c) Velocity of rotation increases => sphere to disk.
d) Most of mass near center of disk => proto-sun.
=> Sun turns on - H + H = He -> nuclear fusion
e) Planets form by chemical condensation/accretion.
Evidence
1) planets orbit in same plane
2) planets rotate in same direction as they revolve around the sun
3) Terrestrial versus Jovian planets
4) young stars observed surrounded by flattened disks of gas and dust
ORIGIN OF EARTH
a. Origin=> 4.6 b.y. ago => condensation/accretion
b. Earth heats up
c. Density Differentiation