General astronomy

General astronomy

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General astronomy

anomalistic year

Astronomy; General astronomy

1) A period of time based on the revolution of the Earth around the Sun, where a year is defined as the mean interval between successive passages of the Earth through perihelion. 2) The interval ...

antapex

Astronomy; General astronomy

The direction in the sky away from which the Sun seems to be moving (at a speed of 19.4 km s-1) relative to general field stars in the Galaxy.

A measure of time used by astronomers; UT conforms (within a close approximation) to the mean daily (apparent) motion of the sun. UT is determined from observations of the diurnal (daily) motions of ...

total (visual) magnitude

Astronomy; General astronomy

Total, integrated magnitude of a comet's head (meaning coma + nuclear condensation). This can be estimated visually, as the comet's "total visual magnitude". The variable m 1 , usually found in comet ...

terrestrial dynamical time (TDT)

Astronomy; General astronomy

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 ...

right ascension

Astronomy; General astronomy

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 ...

perigee

Astronomy; General astronomy

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 ...