Allison Thompson Chapter 6 Notes

What does the Solar System look like?
* Tiny planets with clear patterns and motions.
* Planets are tiny compared to the distance between them.

The Sun:
* Over 99.9% of the Solar System's mass
*Mostly H/HE
*Converts over 4 million tons of mass into energy

Mercury:
* Made of metal and rock
* Desolated craters with long, tall, steep cliffs
* Very hot and very cold.

Venus
* Nearly Earth's size
* Hellish conditions
* Hotter than Mercury
* Atmospheric pressure as deep as 1km in the ocean
* No oxygen/ no water

Earth
* Oasis of life
* Only planet with liquid
* Surprisingly large moon

Mars
* Looks like Earth
* Giant Volcanoes, huge canyons, and polar caps.

Jupiter
* Farther from the sun
* Different compositions no solid surface
* Giant for a planet
* Many moons

Saturns
* Giant and gases like Jupiter 
* Most spectural rings of the 4 Jovial Planets
* Many moons
* Currently under observation
* Rings are not solid, made of countless rocks and ice chunks orbiting like a moon.

Uranus
* Much smaller than Jupiter/ Saturn but larger than earth
* Extreme axis tilt
* Moons also tip in their orbit

Neptune
* Very similar to Uranus
* Many moons are unusual. Triton orbits backwards

Pluto
* Misfit among planets
* Comet like positions
*Moon is half size of Pluto

What features our Solar System provide clues to how it formed?
* Sun, planets, and moons orbit in an organized way.
* Terresetrial Planets are rocky, small and close to the sun.
*Jovial Planets are large, gasous and far from the sun.

What theory best explains the features of our solar system?
* Nebular Theory

Where did the solar system come from?
* The cloud of gas that gives birth to our solar system resulted in from the recycled of gas through many generation of stars within our galaxy.

What caused the orderly pattern of motions in our solar system?
* As gravity forced the cloud to become smaller, it begun to spin faster.
*As gravity forced the cloud to shrink, it spins faster.
* Collisions forced the cloud to compress into a disc.
* Collisions between gas particles gradually reduce random motions
* Collisions between gas particles all reduce up and down motions
* Spinning cloud flattens as it shrinks

Why are there two types of planets, when all planets are formed from the same nebula?
* As gravity causes clouds to contract, it heats up .
* Inner disks are hotter than outer parts
* Rocks can be much more solid at higher temperatures than ice. 
* Inner frost line is to hot for hydrogen compounds to form ice
* Outer frost line is cold enough to form ice
* Tiny solid particles stick together
* Gravity draws planetesimals to form planets. Process is called accretion
* Gravity of rocks and ice in jovial planets draws in H and HE
* Moons of jovial planets form in miniature disks

Why are there two types of planets?
* Outer planet gets bigger because of the abundance of hydrogen compounds
* Outer planets accrete and keep H/He gases

When did the planets form?
* We cannot find the age of planets.

How do we detect planets around other stars?
* By looking for periodic motion as the stars orbit.

What have other planet systems taught us about our own?
* Planetary systems exhibit a surprising range of layouts, suggesting  that jovial planets sometimes migrate inward from where they were born. It shows that the nebular theory is incomplete.