Astronomical Algorithms


The Semidiameter of a celestial body such as the Sun, Moon, or a planet, is his apparent equatorial radius expressed as an angle.

The general formula is S = S0

S semidiameter
S0 the body's semidiameter at unit distance (1 AU)
Δ the body's distance to the Earth in AU.

Current Time

Semidiameter of the Sun

For the Sun S0=15'59".63 = 959".63
Current Sun distance  UA
Semidiameter of the Sun  "

Semidiameter of the Moon

For the Moon S0=2".396
Current Moon distance  UA
Semidiameter of the Moon  "