- Отрасли: Astronomy
- Number of terms: 6727
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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 ...
The scientific study of rocks. This is the field within geology that focuses on the origin, occurrence, formation, structure, and composition of mineral assemblages, and classification of rocks.
Industry:Astronomy
An element with atomic number 26; symbol: Fe. Iron is one of the most abundant elements in the rocky planets. It is the most abundant element in the metallic cores of the inner planets.
Industry:Astronomy
Study of layered rock to understand the sequence of geological events. Normally, older layers are on the bottom unless the sequence has been overturned or disrupted.
Industry:Astronomy
A natural solid object (metallic or stony/silicate) larger than 10 µm (microns) that has traveled through space, by natural means from the celestial body on which it formed, and has landed on Earth or other planetary body or artificial body/satellite (larger than itself). Most meteorites come from asteroids, but a small number found on Earth come from the Moon (see Lunar meteorites) or Mars (see Martian meteorites). Meteorite types include: iron, stony iron, chondrite, carbonaceous chondrite, and achondrite. A primitive meteorite is defined as a chondrite that experienced minimal heating and aqueous alteration on its parent asteroid. Primitive meteorites have the highest concentrations of presolar grains. (See "Meteors, Meteorites, and Impacts" from The Eight Planets website. ) Meteorites between 10 µm (microns) and 2 mm in size are called "micrometeorites. " Meteorites collected on Earth are named for the location where they are found.
Industry:Astronomy
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
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
An element with atomic number 7; symbol: N. It is common in Earth's atmosphere and along with hydrogen, carbon, and oxygen is essential for life.
Industry:Astronomy
