Planetesimals

Definition

Planetesimals are small celestial objects that formed from dust and gas in the early solar system. They serve as the building blocks of planets through a process called accretion.

5 Must Know Facts For Your Next Test

1. Planetesimals range in size from a few kilometers to hundreds of kilometers in diameter.
2. They form through the process of coagulation of dust grains within a protoplanetary disk.
3. Collisions between planetesimals can lead to the formation of planetary embryos or protoplanets.
4. The composition of planetesimals depends on their distance from the Sun, with those closer being rockier and those farther away containing more ice.
5. Planetesimals played a crucial role in clearing out debris from the early solar system, helping to shape its current structure.

Review Questions

• What is the primary role of planetesimals in the formation of planets?
• How does the distance from the Sun affect the composition of planetesimals?
• Describe the process by which planetesimals form within a protoplanetary disk.

Related terms

Protoplanetary Disk:

A rotating disk of dense gas and dust surrounding a newly formed star, where planets may eventually form.

Accretion:

The process by which particles stick together and grow larger by colliding and merging.

Protoplanet: A developing planetary body that grows by accumulating material through collisions and gravity.