Astro*Dictionary
by Michael Erlewine

2 articles for
"Semi-Diameter"

One-half the observed angular width of a body, usually measured in degrees and minutes. Identical to the observed angular radius of a body. The Semi-diameter of the Sun at mean distance is 15'59.63"; the Moon's semi-diameter is 15'32.6" at mean distance.

 

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♦ Astronomy

One-half of the standard width of a visible body measured in degrees and minutes. The average semi-diameter of the Sun is sixteen minutes of arc, and of the Moon is 14.8 minutes of arc.

 

See also:
♦ Astronomy