Question

Which of these is the best description of the accretion of planetessimals?

1) small objects became stable and did not change in size
2) many smaller objects were collected into just a few large ones
3) large objects were broken apart to form asteroids and comets
4) one massive object broke apart to form the planets that we now observe

Answer 1

Accretion of planetesimals describes how many small objects in the solar nebula coalesced to form larger ones, ultimately leading to the formation of protoplanets and the planets in our solar system. Option 2 is the correct answer.

Step-by-step explanation:

The best description of the accretion of planetesimals is that many smaller objects were collected into just a few large ones. Planetesimals are initially formed from dust grains in the solar nebula, which condense and coalesce to form larger chunks several kilometers in size.

As they grow in size due to the process of accretion, these planetesimals attract each other gravitationally, leading to further growth. Eventually, some become large enough to be considered protoplanets, the immediate precursors to actual planets. The process is violent, with frequent collisions contributing not only to their growth but also sometimes disrupting the accretion process.

Over time, most of the debris in the solar system was swept up or ejected, leading to the formation of the planets as we know them today, while remnants became asteroids, comets, and other small objects in the asteroid and Kuiper belts.