6 Terms
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General astronomy
Industry: Astronomy
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General astronomy
julian date (JD)
Astronomy; General astronomy
The interval of time in days (and fraction of a day) since Greenwich noon on Jan. 1, 4713 BC. The JD is always half a day off from Universal Time, because the current definition of JD was introduced ...
extinction, atmospheric
Astronomy; General astronomy
The diminishing of light from astronomical objects due to the earth's atmosphere, in which molecules (air, dust, etc.) of the atmosphere absorb, reflect, and refract light before it reaches the ...
equinox
Astronomy; General astronomy
Either of the two points (vernal, autumnal) on the celestial sphere where the ecliptic (which is the apparent path of the sun on the sky) intersects the celestial equator. Due to precession, this ...
ephemeris time (ET)
Astronomy; General astronomy
Determined in principle from the sun's apparent annual motion, ET is the numerical measure of uniform time, which is the independent variable in the gravitational theory of the earth's orbital ...
ephemeris
Astronomy; General astronomy
A table listing specific data of a moving object, as a function of time. Ephemerides usually contain right ascension ("R. A. " in these web pages) and declination ("Decl. " in these web pages), ...
astronomy
Astronomy; General astronomy
The scientific study of the universe and the objects in it, including stars, planets, and galaxies.
constellation
Astronomy; General astronomy
Group of stars that is named after and shaped somewhat like an animal, a person, or an object.
