Chapter 8

 

Solar system formation once more, this time with the explanation

 

What does a good theory of the formation of the Solar System have to explain?

1.   The patterns of motion

Nearly circular; Coplanar; Prograde revolution; Prograde rotation,

 

2.   Two types of planets

 

3.    Properties of asteroids and comets

 

4.   Don’t forget the exceptions

Orbits: Pluto and Mercury; Tilt: Uranus, Pluto; Rotation: Venus, Uranus; Pluto

Pluto is a Kuiper Belt object

 

A Theory of Formation

 

“From dust (and gas) we came and dust (and gas) we shall return.”

globules

 

 

for the galaxy

 

So how does it all come together?  The movie

Disk is ‘pre-flattened’ by magnetic fields 

       Rotation is in preferred direction (hard to swim up stream)

         Accretion help circularize orbits

 

Outside evidence  a  b  c  d  more disks in IR

 

 

How to build a planet (or a few)

 

First condense the gas

Temperature gradient caused by the protosun

The frost line

Accretion   small,  then larger

                 Evidence meteorites  close-up

         Nebular capture

 

         Clean up – the solar wind

         Slow the Sun down magnetic braking

 

Then comes Planetary Migration and its results

 

After its all over : Leftovers

         Comets and asteroids

         Early and Late bombardment

         Some gets captured - moons

Formation of our moon

 

So, what have you done to me lately?

         Shoemaker-Levy 9  impacts Jupiter

 

Summary

 

How old is the solar system?

         4.56 billion years

         radioactive dating