Late Heavy Bombardment

…often referred to as the Late Heavy Bombardment, can be seen in the ancient, heavily cratered terrains of the Moon, Mars, Mercury, and many other bodies.

…was dispersed, which caused the Late Heavy Bombardment, an event of heavy cratering on the inner terrestrial planets that happened about four billion years ago. A small remnant of the disk became the Kuiper belt, and some planetesimals were captured, becoming Neptune’s Trojan asteroids (see below Moons).