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The layers of the Earth, a differentiated planetary body. In planetary science, planetary differentiation is the process by which the chemical elements of a planetary body accumulate in different areas of that body, due to their physical or chemical behavior (e.g. density and chemical affinities).
The rain-out model is a model of planetary science that describes the first stage of planetary differentiation and core formation. According to this model, a planetary body is assumed to be composed primarily of silicate minerals and NiFe (i.e. a mixture of nickel and iron). If temperatures within this body reach about 1500 K, the minerals and ...
The radioactive system behind hafnium–tungsten dating is a two-stage decay as follows: 182 72 Hf → 182 73 Ta e − ν e 182 73 Ta → 182 74 W e − ν e. The first decay has a half-life of 8.9 million years, while the second has a half-life of only 114 days, [7] such that the intermediate nuclide tantalum-182 (182 Ta) can effectively be ignored.
A major source of differentiation is fractionation, an unequal distribution of elements and isotopes. This can be the result of chemical reactions, phase changes, kinetic effects, or radioactivity. [1]: 2–3 On the largest scale, planetary differentiation is a physical and chemical separation of a planet into chemically distinct regions. For ...
A planetary core acts as a heat source for the outer layers of a planet. In the Earth, the heat flux over the core mantle boundary is 12 terawatts. [30] This value is calculated from a variety of factors: secular cooling, differentiation of light elements, Coriolis forces, radioactive decay, and latent heat of crystallization. [30]
Core–mantle differentiation is the set of processes that took place during the accretion stage [1] of Earth's evolution (or more generally, of rocky planets) that results in the separation of iron-rich materials that eventually would conform a metal core, surrounded by a rocky mantle.
A theoretical planet that has undergone planetary differentiation but has no metallic core. Not to be confused with the Hollow Earth concept. Desert planet: A terrestrial planet with an arid surface consistency similar to Earth's deserts. Mars: Gas dwarf: A low-mass planet composed primarily of hydrogen and helium. GJ 1214 b: Gas giant
Grains eventually stick together to form mountain-size (or larger) bodies called planetesimals. Collisions and gravitational interactions between planetesimals combine to produce Moon-size planetary embryos (protoplanets) over roughly 0.1–1 million years. Finally, the planetary embryos collide to form planets over 10–100 million years. [20]