General astronomy

General astronomy

Industry: Astronomy

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General astronomy

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 error).

perihelion

Astronomy; General astronomy

The point where (and when) an object orbiting the sun is closest to the sun.

perturbations

Astronomy; General astronomy

Gravitational influences ("tugging" and "pulling") of one astronomical body on another. Comets are strongly perturbed by the gravitational forces of the major planets, particularly by the largest ...

phase angle

Astronomy; General astronomy

For a solar system object besides the earth and sun, the angle between the earth and the sun (or the earth's elongation from the sun) as seen from that third object. The phase angle is given in ...

refractor

Astronomy; General astronomy

A telescope that uses as its primary optical element a lens. Binoculars are a type of refractor. In general, refractors are much more expensive to build and buy than are reflectors.

reflector

Astronomy; General astronomy

A telescope that uses as its primary optical element a mirror. Nearly all large telescopes in use today by amateur and professional astronomers are reflecting telescopes.