Page 1, Review of our Solar System [Next Page] [Class Home Page] Text Pages 104-110

We've discussed the Nebular Theory for solar system formation. The development of that theory was strongly based on direct observations: of proto-solar systems around other young stars, but also in noticing characteristic patterns in the Solar System. These can be used as 'hints' as to how things have come to be in our Solar System. We begin with an overview of our Solar System. For still more information, go here.

1) All the planets orbit in the same direction around the Sun.
Almost all share the same rotational direction, consistent with the Sun's rotational direction. (except Venus rotates backwards, Pluto & Uranus have highly tilted rotational axes.)


2) Planets are all in the same flattened plane, aligned with the Sun's equator, and follow highly circular orbits.
Exception (again) Pluto, who's orbit is highly elongated and tilted relative to the plane of the solar system.

3) Composition
The composition of the planets is related to their distance from Sun. In broad terms, they can be divided into:


Terrestrial Planets: Mercury, Venus, Earth & Mars are solid rocks with very thin (or no) atmosphere.
Jovian (gas giant) Planets: Jupiter, Saturn, Uranus, Neptune are enormous thick atmosphered planets, with possible solid cores.
Pluto Small, icy rock, like other objects found at that distance.
Space Debris Asteroids, Comets and Meteors.