- 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 ...
An element with atomic number 2; symbol: He. It is the second most common element in the Sun and outer planets, but rare on the rocky planets.
Industry:Astronomy
General term referring to the layers of fragmental and loose, incoherent, or unconsolidated rock, mineral, and glass fragments of any origin (residual or transported) that accumulate on the surface. On the Moon, this blanket of debris is produced by impacts.
Industry:Astronomy
Point in the elliptical orbit of a comet about the Sun in which it passes closest to the Sun.
Industry:Astronomy
Person specializing in the scientific studies of meteorites. They work at universities, government laboratories (such as at NASA Centers), or associated with important meteorite collections (such as natural history museums in many different countries, and the Vatican. )
Industry:Astronomy
Igneous rock, found in the lunar highlands, composed of plagioclase and olivine.
Industry:Astronomy
A hole or depression. Most are roughly circular or oval in outline. On Earth most natural craters are of volcanic origin. On the Moon most are of impact origin.
Industry:Astronomy
Term used to describe the layer of magma, hundreds of kilometers thick; thought to have covered the Moon 4. 5 billion years ago. The timing, duration, cooling rates, convection, partial melting, lateral and vertical chemical variations, and overturn of the lunar magma ocean are topics of continuing research.
Industry:Astronomy
Forces that alter the path of a comet, which are not caused by gravitational interaction with the Sun and planets. Typically this refers to uneven outgassing from vents on the comet, which serve to act like rocket nozzles.
Industry:Astronomy
Термін використовується для опису шарі магми, сотні кілометрів товсті; думав, що буде викладено 4 місяці. 5 мільярдів років тому. В терміни, тривалість, охолодження ставки, конвекції, часткове плавлення, бічний і вертикальних хімічних змін і overturn Місячне магми океану наведено розділи постійних досліджень.
Industry:Astronomy
