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In astronomy or planetary science, the frost line, also known as the snow line or ice line, is the minimum distance from the central protostar of a solar nebula where the temperature is low enough for volatile compounds such as water, ammonia, methane, carbon dioxide and carbon monoxide to condense into solid grains, which will allow their accretion into planetesimals.
The orbits of Solar System planets are nearly circular. Compared to many other systems, they have smaller orbital eccentricity. [70] Although there are attempts to explain it partly with a bias in the radial-velocity detection method and partly with long interactions of a quite high number of planets, the exact causes remain undetermined. [70] [74]
Because the frost line accumulated large amounts of water via evaporation from infalling icy material, it created a region of lower pressure that increased the speed of orbiting dust particles and halted their motion toward the Sun. In effect, the frost line acted as a barrier that caused the material to accumulate rapidly at ~5 AU from the Sun.
[18] [19] The formation of planets and moons in geometrically thin, gas- and dust-rich disks is the reason why the planets are arranged in an ecliptic plane. Tens of millions of years after the formation of the Solar System, the inner few AU of the Solar System likely contained dozens of moon- to Mars-sized bodies that were accreting and ...
In general terrestrial planets have either surfaces of ice, or surface crusts of rock or regolith, with distinct terrains. Water ice predominates surfaces in the Solar System beyond the frost line in the Outer Solar System, with a range of icy celestial bodies. Rock and regolith is common in the Inner Solar System until Mars.
The widely accepted modern variant of the nebular theory is the solar nebular disk model (SNDM) or solar nebular model. [1] It offered explanations for a variety of properties of the Solar System, including the nearly circular and coplanar orbits of the planets, and their motion in the same direction as the Sun's rotation.
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Definition of planet (1 C, 10 P) E. ... Formation and evolution of the Solar System; Frost line (astrophysics) G. ... Satellite system (astronomy)