- Branche: 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 angular distance North or South from the Earth's equator measured in degrees on the meridian of a point; Equator being 0° and the poles 90° N and 90° S.
Industry:Astronomy
Angle between the plane of the object's orbit and the ecliptic (defined by Earth's orbit).
Industry:Astronomy
The time when the Sun is 6-12 degrees below the horizon. Sky begins to get noticeably bright.
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
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
An imaginary great circle in the sky drawn concentric to the Earth's equator.
Industry:Astronomy
Astronomical brightness measured on a logarithmic scale, based on the ancient practice of noting that the brightest stars in the sky were of "first importance" or "first magnitude", the next brightest being "second magnitude" etc. The human eye is a logarithmic detector, and in 1854 Pogson formalized this scale and defined a difference of 5 magnitudes to be exactly a factor of 100 in brightness. The scale is calibrated to the bright star Vega which is defined to have a magnitude of 0. For reference, the faintest naked-eye magnitude visible from a dark site is +6. Comet C/1996 B2 Hyakutake reached magnitude 0 in late March 1996.
Industry:Astronomy
