Astro*Dictionary
by Michael Erlewine

5 articles for
"Astronomical"

Astronomical Day [Astro*Index]

A 24-hour day, beginning at midnight (0h). Thus, noon is 12:00, 1:00 PM = 13:00. The first second of the day is: 00:00:01. The last second of the day is: 23:59:59. Also called 24-hour, or "military" time, which is in common use in European countries.

 

See also:
♦ Time ♦ Day

 

Astronomical Time [Astro*Index]

Clock or Civil Time.

 

See also:
♦ Time ♦ Clock Time ♦ Civil Time

 

Astronomical Unit   AU [Astro*Index]

(au).

A system of measurement used within our solar system based on the mean distance between the Earth and the Sun – 92,957,130 miles (149,600,000 km).

The relation of planets and other bodies to the Sun is expressed using the au as a measuring stick. For example, the mean distance of Saturn from the Sun is 9.54 au; the semimajor axis of the Earth's orbit is 1.000000031 au.

 

See also:
♦ Ellipse

 

Astronomical Unit   AU [Munkasey M.]

A unit of long distance measure used within the Solar system.

It is based upon the mean Earth to Sun distance and is equal to 93 million miles (150 million km).

 

See also:
♦ Ellipse

 

Astronomical Unit [DeVore]

Mean distance of Earth to Sun, or 92,900,000 miles; employed as a unit for indicating intra-solar system distances.

 

See also:
♦ Time ♦ Clock Time ♦ Civil Time