Conversation so far:
earth is what number planet from the sun
Earth is the third planet from the Sun.
what is the fourth planet from the sun
Mars is the fourth planet from the sun.
does mars have moons
Mars has two moons, Phobos and Deimos, which are small and irregularly shaped.

Question: why are the moons small and irregularly shaped
Self-contained rewrite: why are mars's moons small and irregularly shaped