Protoplanet
Protoplanet [from Greek prõtos "first"] is the name given to the precursor of a planet according to the most common theory. It is the second development stage of planets after the planetesimals . Protoplanets appear in both Kant's and Laplace's theory , the first hypotheses on the formation of the solar system .
development
When the main mass of the solar nebula condensed into a protostar , the gas and dust particles remaining in the vicinity formed a circumolar accretion disk . In this protoplanetary disk , dust particles have accumulated through accretion or sticking due to the force of adhesion and cohesion to form planetesimals that are no more than about kilometer-sized . Due to their gravitation, these united to form larger densities of matter, the first protoplanets, which could attain the size of dwarf planets . They were already massive enough to achieve an approximately spherical shape through a hydrostatic equilibrium and to form a shell structure through differentiation of their interior .
The further growth beyond the size of the moon to that of full-grown planets was not possible through gravity alone, but came about through collisions on intersecting orbits , which also led to shattering.
Examples
According to the most widespread theory of the formation of the earth's moon, a protoplanet the size of Mars ( called Theia ) collided with the proto-earth, which led to the current mass of the earth and at the same time to the formation of the moon.
The asteroid Vesta in the inner asteroid belt is a protoplanet that has not evolved into a planet. Also Pallas is considered leftover Protoplanet.
See also
Web links
- How quickly did the earth come into being? from the alpha-Centauri television series(approx. 15 minutes). First broadcast on Feb 2, 2005.
- Spektrum .de: Pictures from the cosmic delivery room on September 25, 2019
Individual evidence
- ↑ Mike Wall: Huge Asteroid Vesta Actually an Ancient Protoplanet. In: space.com. May 10, 2012, accessed November 17, 2015 .
- ↑ McCord, TB; McFadden, LA; Russell, CT; Sotin, C .; Thomas, PC: Ceres, Vesta, and Pallas: Protoplanets, Not Asteroids . In: Transactions of the American Geophysical Union . 87, No. 10, 2006, p. 105. bibcode : 2006EOSTr..87..105M . doi : 10.1029 / 2006EO100002 .