Large regular moons probably formed:
A) when passing asteroids were captured by the gravitational field of their planet
B) at the same time as their planets and grew by accretion
C) after a collision between a planet and a large asteroid fractured off a piece of the planet
D) after the period of heavy bombardment in the early Solar System
E) after a planet got kicked out of its orbit and was gravitationally captured by another planet

Question

Quizplus · Accepted Answer

Large regular moons probably formed at the same time as their planets and grew by accretion. This is supported by the fact that many large moons in our Solar System have similar compositions to their parent planets, indicating that they formed from the same material. Additionally, simulations of planetary formation suggest that moons can form from the same protoplanetary disk as their planets.

Large Regular Moons Probably Formed