noun
- small rocky or icy bodies that formed in the early solar system and served as building blocks for planets
Usage: astronomy; plural form
Examples
- Planetesimals collided and merged to form the rocky planets.
- Scientists study meteorites to learn about ancient planetesimals.
- The asteroid belt contains remnants of planetesimals that never formed a planet.
- Planetesimals in the outer solar system were rich in ice and organic compounds.
- Computer models show how planetesimals accumulated into larger bodies.
- Some planetesimals were heated by radioactive decay in their cores.