Frost line (astrophysics)

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In astronomy or planetary science, the frost line, also known as the snow line, refers to a particular distance in the solar nebula from the central protosun where it is cool enough for hydrogen compounds such as water, ammonia, and methane to condense into solid ice grains. Depending on density, that temperature is estimated to be about 150K. The term is borrowed from the notion of "frost line" in soil science.

The lower temperature in the nebula beyond the frost line makes many more solid grains available for accretion into planetesimals and eventually planets. The frost line therefore separates terrestrial planets from jovian planets.

[edit] See also

• Solar nebula
• nebular hypothesis