- Settore: 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 ...
Single-celled microorganisms whose cells lack a nucleus. Bacteria comprise a major domain of life called prokaryotes. In contrast, the cells in eukaryotes have a well-defined nucleus; eukarya include molds, plants, and animals. Another major domain is called archaea, microorganisms with genetic features distinct from prokarya and eukarya. Most methane-producing bacteria are actually archaea, but for simplicity many biologists informally refer to all non-eukaryotes as "bacteria. "
Industry:Astronomy
Conventional unit of pressure when discussing the deep Earth: 1 GPa = 10 kilobars = 10,000 times air pressure at sea level.
Industry:Astronomy
Термин, приложени към разтопена скала във вътрешността на една планета или Луната. Когато достигне повърхността, магма се нарича лава.
Industry:Astronomy
Района на пространството между орбитите на Марс и Юпитер, от 2. 1 до 3. 3 AU, където се намират повечето астероиди.
Industry:Astronomy
The Sun and all the objects (planets, moons, asteroids, and comets) that orbit the Sun.
Industry:Astronomy
An enormously bright, energetic, catastrophic explosion that occurs at the end of the lifetime of a massive star whose core collapses. A star must have at least nine times the mass of the Sun to undergo a core-collapse supernova. The extreme heat generated by the explosion makes elements heavier than iron, this is called supernova nucleosynthesis. See also r-process and s-process, and stellar nucleosynthesis.
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 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
The scientific study of minerals. This is the field within geology that focuses on the chemistry, structure, properties, and classification of minerals.
Industry:Astronomy
Apparent motion of a nearby object as projected against more distant background objects due to the motion of the observer.
Industry:Astronomy
