Introduction to the Solar System

Topographic map of the Earth from satellite data
Spreading centers
Subduction zones
Earthquakes -- along rifts and behind subduction zones

Pythagoras -- 525 BC, 175 years before Aristotle, proposed that the sun was the center of the Universe
Pangea was the last supercontinent, broke up 170 My ago. It was made from Gondwanaland and Laurasia, so Gondwanaland is older but not all the continents
Older supercontinents-- Rodina 1 By ago, Ur 3 By ago

Sunlight -- air heats and rises over equator and sinks near poles. This is N-S motion and is called Hadley Circulation
Earth is spinning
Equator air is moving faster than pole air
So when air goes from equator to pole, in N, it has excess E velocity
It curves to the right -- This is Coriolis Force
If it spins around a low pressure zone--hurricanes

Blue light is more easily diverte or scattered by air molecules
It goes bounncing all over the sky until you can see this diffuse, almost indescribable glow that is the blue sky
Red light gets through easily

When the sun is low on the horizen, where the air is thickest, all the blue light on the way from the sun to you has been scattered away into the sky. What's left is red, and that's what you see

Sunlight comes right through the air, heats the ground. Air is transparent to sunlight.
Ground takes the light energy and turns it into heat energy
The sky is not transparent to heat
Heat gets trapped and heats up the air
It has nothing to do with clouds.
Water vapor does most greenhouse warming, with CO2 a distant 2nd

Ozone is O3, formed by the breakup up oxygen gas (O2) by ultraviolet light, and its recombination into 3 oxygen atoms to form one molecule
It is formed in the stratosphere
Ozone is the main absorber of dangerous solar UV, so that it doesn't reach the ground and destroy crops and living tissue
Cl and F from CFC's (chloroflourohydrocarbons) can destroy ozone by their
chemical effects in cold regions of the polar stratosphere

Earth is a big bar magnet
Something to do with a turning, molten, conducting core, and electric current flowing through the liquid
Magnetic field goes way out into space, where it gets tangled up with the solar magnetic field and the solar win
Solar wind is a wind of particles (H and e) streaming off the sun all the time. But when there's a solar storm, there are a lot more of them
The particles come streaming along the Earth's polar magentic field line, hit the upper atmospher, and make it glow like a flourescent bulb -- aurora

Same moon, same face, same motions over antiquity
It shone down on dinosaurs, and on the first humans, who could see at night
It's a rocky world with dark gray flows of ancient lavas
Covered with the scars of impacts from the left over rocks, comets and debris left over from the solar system formation

What if you're a painter, and you wanted to experiment with what the moon looked like long ago, when it was 6 times closer. A setting crescent moon
If you understood the moon, you could figure out what it looked like
Moon-Sun-Horizon relationship on board. Two horned view of large setting moon

Start with a new moon
Sidereal period -- with respect to the stars 27.3 days
Earth has moved a little around the sun in this time
The moon (interactive animation) has to rotate a little bit more to get to the same phase (new moon again). It takes 29.5 days, the synodic period

The moon rotates once in the time it takes it to go around the Earth
Thus the moon shows the same face towards the Earth
Board: fixed location on moon, nonrotating moon
Board: fixed location on moon, rotating moon
This is called tidally locked
Gravity pulls more on one side of the Earth (due to the moon) than on the other
As the Earth rotates, the tides stay fixed towards the moon and seem to happen on a fixed point on Earth every 12 hours -- Ocean tides
There are also body tides, operating on the Earth itself, which is slightly elastic
Same thing for Earth on the moon, but because the Earth is more massive, the body tides are stronger -- tidally locked moon, also called synchronous rotation
The Earth is also braking -- the days are getting longer
The moon is also slowly receding due to tides: when the Moon formed, it was about 6 times closer, and therefore 6 times bigger

Many theories, most had a lot of problems. The moon is unusual, because most planets have small moons (exception: Pluto)
Evidence from Apollo
Old, old rocks (radioactive dating)
No water
Very little iron
Composition of moon -- just like Earth's mantle
Giant Impact hypothesis
Combining of Apollo evidence and computer modeling 1970's, 1980's, up to today
When the Earth had just formed, a Mars sized object (2 X moon) hit the Earth
Blasted mantle material into space
Computer models say:
No iron core made it into space
Any water vaporized and was gone
Rocks blasted into space formed a ring, which coelesced into a rocky moon without iron and water

VIDEO: FOR ALL MANKIND (First half)

6/6/96