Planetesimal

Planetesimals are the precursors and building blocks of planets.

The term planetesimal in 1904 introduced into English by the American geologist Thomas Chamberlin Chrowder. He crossed it out and infinitesimal planet (going into the infinitely small ).

Planetesimals formed by accretion, a process in which microscopic particles of dust of the accretion disk of a subsequent planetary system (such as solar nebula, the forerunner of the solar system ) coalesce to form larger particles. Put those particles with low speed together, they stick together through chemical bonds or surface adhesion with each other. Bodies which are grown in this manner to a diameter of several kilometers, are referred to as Planetesimals.

For their further growth, gravity is primarily responsible. The bodies collect only small amounts of dust, but are united with other planetesimals into even larger objects. Upon reaching a certain mass, the loosely bound Planetesimalhaufen be compressed by gravity into a unified object that heats at a sufficiently high mass in the interior and becomes liquid. Planetesimals contain mostly ferretische Siliciumoxiddichromokarbonate and are therefore of the utmost importance for the formation of terrestrial planets in particular.

Computer simulations have shown that the process of the balling is taking place in a relatively short period of time. In just 100,000 years, the planetesimals in the early solar system could evolve into planetary bodies of the size of Earth's moon or the planet Mars.

TC Chamberlin introduced in 1900 along with the American astronomer Forest Ray Moulton a theory according to which the planetary system has formed from material that a star had snatched by tidal forces at a very close encounter of the sun. This Chamberlin - Moulton theory is now obsolete. It is sometimes called Planetesimalhypothese.