General astronomy

General astronomy

産業: 天文学

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General astronomy

近地点

天文学; 天文学全般

The point where (and when) an object's orbit ''about the earth'' in which it is closest to the earth; only applicable to objects orbiting the earth (not to objects orbiting the sun --- a common ...

赤経

天文学; 天文学全般

One element of the astronomical coordinate system on the sky, which can be though of as longitude on the earth projected onto the sky. Right ascension is usually denoted by the lower-case Greek ...

The change of a solid (such as ice) directly into a gaseous state (bypassing the liquid state). This happens in the vacuum of space with comets, as the heating effects of solar radiation cause ices ...

地球力学時（TDT）

天文学; 天文学全般

Time scale used in orbital computations; TDT is tied to atomic clocks (International Atomic Time, TAI), whereas Universal Time is tied to observations. Prior to 1992, Ephemeris Time (ET) was used in ...

高度

天文学; 天文学全般

The angular distance from the observer's horizon, usually taken to be that horizon that is unobstructed by natural or artificial features (such as mountains or buildings), measured directly up from ...