- Industry: 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 ...
An igneous rock made up almost entirely of plagioclase feldspar. This rock dominates the lunar highlands.
Industry:Astronomy
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
A large cloud of dust and gas which escapes from the nucleus of an active comet.
Industry:Astronomy
Buried mare basalt lavas on the Moon. Many light plains in the lunar highlands have impact craters surrounded by dark piles of ejecta, nicknamed "dark-haloed craters. " The dark-haloed craters formed when mare basalt lava flows were covered with ejecta from large impact craters and basins, and then small craters punctured through the ejecta to toss out mare basalt.
Industry:Astronomy
A precise definition of the isotopic composition of water on Earth. It serves as a reference standard for comparing hydrogen and oxygen isotope ratios. For example, cosmochemists measure the <sup>17</sup>O / <sup>16</sup>O and <sup>18</sup>O / <sup>16</sup>O ratios in terms of deviations in parts per thousand from a standard (delta <sup>18</sup>O and delta <sup>17</sup>O). The usual standard is SMOW.
Industry:Astronomy
The configuration (shapes, positions, arrangements) and relief (elevations, slopes) of the land surface.
Industry:Astronomy
The percentage of the total volume of rock or soil that consists of open spaces. (The space between particles is called pore space. )
Industry:Astronomy
The fourth state of matter beyond solid, liquid, and gas. Plasma may be the most common state of matter in the universe. Our Sun is plasma. In space science, plasma is hot, ionized gas--a mixture of electrons (negative electric charge) and protons (positive electric charge). Plasma conducts electrical currents and responds to electromagnetic fields.
Industry:Astronomy
