Characteristics of the Solar System (formation theory must explain all)
1. All of the planets orbit in the same direction and in the same plane. (Within a few degrees) This plane corresponds with the equator of the sun.
- Exceptions: Mercury (7 degrees), Pluto (17 degrees)
2. Most of the planets rotate in the same direction and have their equators roughly aligned with the plane of the solar system.
- Exception: Venus rotates in the opposite direction (retrograde).
- Exception: Uranus and Pluto highly tilted (~90 degrees) with respect to the plane of solar system.