# How often does the moon "set" for us compared to the sun?

I am working on a game, and I have a day/night cycle. Currently I have the sun. Currently every "sun day" is 24 hours, with that being said, how long is every "moon day"? In other words, how much does the moon lag behind the sun. I just need to figure out what the moons speed should be in relativity to the sun. I've done some searches, but wasn't quite sure how to properly word this question.

• the sun and the moon are essentially static... it's the Earth that rotates in 24 hours. The moon falls behind by about 50 minutes every day.
– f.thorpe
Jun 9 '15 at 2:41
• @farrenthorpe The Earth rotates in 23 h 56 m 4.1 s.
– gerrit
Jun 9 '15 at 10:02
• @gerrit yes with respect to the stars, not with respect to the sun. Not sure what your point is here other than to prove you know decimal places?
– f.thorpe
Jun 9 '15 at 12:30
• @farrenthorpe My point is that a solar day does not correspond to a single rotation of the Earth, but that it is a single rotation of the Earth /plus/ a fraction of the Earth rotation around the Sun. This is quite relevant for astronomical questions such as this one, as it causes the length of a solar day to vary during the year, which makes the answer to Jaydens question more involved. I'm not sure if a rotation on an axis is a relative or an absolute quantity.
– gerrit
Jun 9 '15 at 13:13
• Technically this is probably a question for astronomy.se, but we should be able to provide an answer here... The Google terms for the comment conversation above are "solar day" vs "sidereal day". The "moon day", as you put it is a little less straightforward. I'll try to put an answer together when near a PC later. Jun 10 '15 at 5:04