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From: George Huxtable (no email)
Date: Wed Dec 07 2005 - 19:15:49 EST
Bill asked-
> Does anyone know the Apparent diameter of Venus viewed from the central
> USA
> about now?
My pocket-calculator program reckons that at today (7 Dec 05), at Greenwich
noon, Venus was .42 AU from the Earth.
An AU (Astronomical Unit) is the mean distance between the Earth and the
Sun, which is 149597870 km
I've found, in an astronomy book, the diameter of Venus to be 7700 miles, or
12389 km. It's an oldish book, so that number may have been superseded, but
surely it will do for us.
So if Venus was at a distance of 1 AU, its angular diameter would be
arc sine 12389 / 149597870 or 0.285 arc-minute.
But it's closer than that, only 0.42 AU, which will make Venus appear
correspondingly larger. So we should divide that amount by 0.42, which gives
0.678 arc-minutes. It's effectively the same, wherever on Earth it is viewed
from.
At its closest, Venus can come to about 0.266 AU.
Hope I have it right.
George.
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