Am I over thinking this question? I know that the Moon's distance from Earch is 384,400 km and has an angular diameter of about 0.5 so my inital line of thought is that if the Moon were twice as far then the arc angle would be 1 degree and if it were half as far away the arc angle would be .25 but somehow I feel I'm missing something here.
2007-09-26 11:57:05 · 3 answers · asked by astronomy dummy 1 in Science & Mathematics ➔ Astronomy & Space
You're right.
Go ahead and celebrate!
2007-09-26 12:07:28 · answer #1 · answered by Bobby 6 · 0⤊ 1⤋
The apparent size of an object is directly related to its actual size and its distance.
A house 2 blocks away looks half as large as the same house only 1 block away.
The moon subtends half a degree (or 30 arcminutes) right now.
If it was twice as far away, it would look half the size (.25 degrees, or 15 arcminutes).
2007-09-26 12:42:20 · answer #2 · answered by Anonymous · 0⤊ 0⤋
Yes, you are. You have it just backwards. If the moon were twice as far away it would subtend about 1/4 degree and if it were half as far, about 1 degree. (Actually, it varies as Φ = k arcsec(1/r), but for small angles it's real close to linear)
Doug
2007-09-26 12:10:30 · answer #3 · answered by doug_donaghue 7 · 0⤊ 0⤋