“ The Big Bang”
=> 14-20 billion years ago the universe began during a cataclysmic
release of energy from a point source of infinite mass.
Evidence:
An Expanding Universe
How do we know the universe is expanding?
a. Expansion is suggested by the “Red Shift” (Hubble, 1927)
b. Red shift can be explained by the Doppler Effect
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
Catastrophic Birth of the Moon
a. glancing blow from Mars-sized object - moon created from the
particle of this object.
Evidence:
- absence of water
- small metallic core
-feldspar-rich outer layer
-rapid rotation
The Origin of the Atmosphere & Oceans
A. Outgassing => “The Big Burp”=> the early Atmosphere
H, H2O (vapor), CH4, NH3
B. Condensation and Comets - source of liquid H2O
=> the early Oceans
=> Where does the salt
come from????
The Archean Earth
1. The consequences of bolide impact.
a. the tilt of the Earth’s Axis
b. craters on the moon
- Jupiter = planetary protection