Checking understanding of space physics and the solar system

5 questions

Assessing knowledge of planetary orbits, solar influences and gravitational forces in the solar system.

Questions

1. Which planet has the shortest orbital period around the Sun?
2. The solar wind emitted by the Sun shapes the magnetospheres of planets that have magnetic fields.
3. Why are the inner planets (Mercury, Venus, Earth, Mars) primarily rocky?
4. What is the primary force that keeps the Moon in orbit around Earth?
5. The heliosphere extends beyond the orbit of Pluto.