Any of innumerable small bodies thought to have orbited the sun during the formation of the planets.
In various theories about the origin of the solar system, any of the small, cold masses of rock or ice that merged to form a planet.
Any of innumerable small bodies of accreted gas and dust thought to have orbited the Sun during the formation of the planets. &diamf3; The theory that explains the formation of the solar system in terms of the aggregation of such bodies is known as the planetesimal hypothesis . According to this theory, first proposed in 1900, the planetesimals formed within a spiral disk of dust and gas surrounding a central nucleus. Their gravitational attraction eventually caused the planetesimals to coalesce into protoplanetary disks from which larger objects such as planets, asteroids, and satellites were formed, while the nucleus coalesced into the Sun.
Origin of planetesimal
- planet (infinit)esimal
From American Heritage Dictionary of the English Language, 5th Edition