Protoplanet: Difference between revisions
No edit summary |
SimDarthMaul (talk | contribs) ←Undid revision 114828025 by 131.109.28.246 (talk) rvv |
||
| Line 1: | Line 1: | ||
Protoplanets are |
Protoplanets are moon-sized planet '''embryos''' within [[protoplanetary disc]]s. They are believed to form out of kilometer-sized [[planetesimal]]s that attract each other gravitationally and collide. According to [[solar nebula|planet formation theory]], protoplanets perturb each other's orbits slightly and thus collide in giant impacts to gradually form the real [[planet]]s. |
||
Early protoplanets had more [[radioactive]] elements, the quantity of which has been reduced over time due to [[radioactive decay]]. Heating due to radioactivity, impact, and gravitational pressure melted parts of protoplanets as they grew toward being [[planet]]s. In melted zones their heavier [[Chemical element|element]]s sank to the center; while lighter elements rose to the surface; such a process is known as [[planetary differentiation]]. Composition of some [[meteorite]]s show that differentiation took place in some asteroids. |
Early protoplanets had more [[radioactive]] elements, the quantity of which has been reduced over time due to [[radioactive decay]]. Heating due to radioactivity, impact, and gravitational pressure melted parts of protoplanets as they grew toward being [[planet]]s. In melted zones their heavier [[Chemical element|element]]s sank to the center; while lighter elements rose to the surface; such a process is known as [[planetary differentiation]]. Composition of some [[meteorite]]s show that differentiation took place in some asteroids. |
||
Revision as of 16:36, 13 March 2007
Protoplanets are moon-sized planet embryos within protoplanetary discs. They are believed to form out of kilometer-sized planetesimals that attract each other gravitationally and collide. According to planet formation theory, protoplanets perturb each other's orbits slightly and thus collide in giant impacts to gradually form the real planets.
Early protoplanets had more radioactive elements, the quantity of which has been reduced over time due to radioactive decay. Heating due to radioactivity, impact, and gravitational pressure melted parts of protoplanets as they grew toward being planets. In melted zones their heavier elements sank to the center; while lighter elements rose to the surface; such a process is known as planetary differentiation. Composition of some meteorites show that differentiation took place in some asteroids.
The giant impact theory proposes that Earth's Moon formed from a colossal impact of a hypothetical protoplanet, named Theia, with Earth early in the solar system's history.
 | This astronomy-related article is a stub. You can help Wikipedia by expanding it. |