- 行业: Astronomy
- Number of terms: 6727
- Number of blossaries: 0
- Company Profile:
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 ...
Radiocarbon, or <sup>14</sup>C, is the unstable, radioactive isotope of carbon having atomic number 6 and atomic mass 14. It is continuously produced in Earth's upper atmosphere by cosmic ray bombardment. In space, <sup>14</sup>C is produced when cosmic rays interact with oxygen in silicate minerals in rocks. The half-life of <sup>14</sup>C is 5730 years, which makes this radioactive isotope suitable for dating rocks and archaeological items as old as about 75,000 years.
Industry:Astronomy
Preserved in primitive meteorites, presolar grains are stardust that formed in stellar outflows or ejecta in the molecular cloud, out of which our Solar System formed.
Industry:Astronomy
A 10 µm to 1-meter-size natural solid object moving in interplanetary space. Meteoroids may be primary objects or derived by the fragmentation of larger celestial bodies, not limited to asteroids. Meteoroids between 10 µm (microns) and 2 mm in size are called "micrometeoroids. "
Industry:Astronomy
Interdisciplinary science that overlaps with geochemistry, geology, astronomy, astrophysics, and geophysics to discover the materials and fundamental processes in the solar nebula and our Solar System. These sciences give us complementary ways of looking at our origins by addressing questions like, How did the Sun and planets form? Where did we come from? Cosmochemistry, because it is a careful examination of the building blocks of the cosmos, also plays an important role in developing local resources on the Moon, Mars, and asteroids, essential to sustained human presence in space.
Industry:Astronomy
In the context of space weathering on the surfaces of airless planetary bodies, sputtering is the process in which atoms on the surface are knocked free by high-speed atomic particles in the solar wind; much higher-energy cosmic rays can also sputter surface materials.
Industry:Astronomy
Dark-colored, fine-grained extrusive igneous rock with about 52 to 63 weight percent silica (SiO<sub>2</sub>). Andesite consists mainly of plagioclase and one or more mafic minerals. The word andesite is derived from the Andes Mountains, located along the western edge of South America, where andesite rock is common.
Industry:Astronomy
A synthetic crystalline compound used as the active medium for certain solid-state lasers.
Industry:Astronomy
The visible light in the sky produced when a meteoroid passes through Earth's atmosphere (can also refer to the glowing meteoroid itself).
Industry:Astronomy
A small, mostly rocky body orbiting the Sun. Asteroids range in size from 1000 kilometers in diameter to tiny objects you could hold in your hand. Most asteroids orbit the Sun between Mars and Jupiter (the Asteroid belt), and are the source of most meteorites. Principal asteroids are: 1 Ceres (a dwarf planet), 2 Pallas, 3 Juno, and 4 Vesta. The majority of asteroids fall into three types: C-type (carbonaceous), S-type (silicate or stony), and M-type (metallic).
Industry:Astronomy
Scientist who studies Earth, its structure, its materials, the physical and chemical processes and changes that occur on the surface and in the interior, and the history of the planet and its life forms. Planetary geologists extend their studies to the Moon, planets, and other solid bodies in the Solar System.
Industry:Astronomy
