- 行业: Astronomy
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Planetary Science Research Discoveries (PSRD) is an educational site sharing the latest research by NASA-sponsored scientists on meteorites, asteroids, planets, moons, and other materials in our Solar System. The website is supported by the Cosmochemistry Program of NASA's Science Mission ...
Rocks that have recrystallized in a solid state as a result of changes in temperature, pressure, and chemical environment.
Industry:Astronomy
Roughly spherical objects found in a type of meteorite called chondrites. Most chondrules are 0. 5 to 2 millimeters in size and are composed of olivine and pyroxene, with smaller amounts of glass and iron-nickel metal. The shapes of the mineral grains in them indicate that chondrules were once molten droplets floating freely in space.
Industry:Astronomy
A primitive meteorite is a chondrite that experienced minimal heating and aqueous alteration on its parent asteroid. Primitive meteorites have the highest concentrations of presolar grains.
Industry:Astronomy
A black, strongly magnetic iron-oxide mineral; Fe<sub>3</sub>O<sub>4</sub>.
Industry:Astronomy
Force per unit area acting on a planetary body resulting in periodic bulging (of the crust and, in the case on Earth, oceans) caused by the gravitational attraction of another object such as the Sun, a moon, or a planet. The alternate growth and decay of a tide in the crust of a planetary body can lead to frictional heating.
Industry:Astronomy
Calcium-aluminum-rich inclusions are found in chondritic meteorites. CAIs are primitive objects that formed in the solar nebula before the planets formed. CAIs are light-colored objects rich in refractory elements (that condense at a high temperature). Besides calcium and aluminum, this includes magnesium, titanium, and rare earth elements. CAIs range in size from about a millimeter to a centimeter. Meteoriticists have identified several distinct varieties of CAIs, but all share a high temperature origin. Some might be condensates from the solar nebula. Other CAIs might be evaporation residues.
Industry:Astronomy
