Late-stage Accretion

Synonyms

Late-stage chaotic growth

Definition

Late-stage accretion refers to the final stage in the formation of terrestrial planets. At the beginning of this stage, the solid mass in the protoplanetary disk is roughly equally divided between planetary embryos and smaller planetesimals. Embryos grow large enough to gravitationally perturb each other onto crossing orbits, triggering a phase of giant embryo–embryo collisions. In most cases, the chaotic growth stage is thought to start 1–10 million years after the start of accretion and to last for another 10–100 million years, generating amounts of collisional debris. The impact that formed the Earth–Moon system is thought to have been the last giant impact on Earth. It occurred during the chaotic growth stage, 4.45 Gy ago (50–100 million years after the start of accretion).

See Also

• Giant Impact

• Moon, Origin of

• Planetesimals

• Planet formation