Terrestrial Planets

Formation And Evolution Of The Solar System - Formation - Formation of Planets
... See also Protoplanetary disc The various planets are thought to have formed from the solar nebula, the disc-shaped cloud of gas and dust left over from the ... The currently accepted method by which the planets formed is known as accretion, in which the planets began as dust grains in orbit around the central protostar ... These rocky bodies would become the terrestrial planets (Mercury, Venus, Earth, and Mars) ...

Geology Of Solar Terrestrial Planets - Formation of Solar Planets - Terrestrial Planets
... That is why the terrestrial planets could not grow very large and could not exert large pull on hydrogen and helium gas ... Even if the terrestrial planets had had hydrogen and helium, the Sun would have heated the gases and caused them to escape ... Hence, solar terrestrial planets such as Mercury, Venus, Earth, and Mars are dense small worlds composed mostly from 2% of heavier elements contained in the solar nebula ...

Nebular Hypothesis - Formation of Planets - Giant Planets
... The formation of giant planets is an outstanding problem in the planetary sciences ... The first one is the disk instability model, where giant planets form in the massive protoplanetary disks as a result of its gravitational fragmentation (see above) ... is thought to be the most promising one, because it can explain the formation of the giant planets in relatively low mass disks (less than 0.1 solar masses) ...

Extrasolar Terrestrial Planets
... See also Super-Earth and Pulsar planet The majority of planets found outside the Solar System have been gas giants, since they produce more pronounced wobbles in the host stars and are thus more easily ... However, a number of extrasolar planets are suspected to be terrestrial ... During the early 1990s, the first extrasolar planets were discovered orbiting the pulsar PSR B1257+12, with masses of 0.02, 4.3, and 3.9 times that of Earth's ...