Moon

[Cuoriousmarta84]

Hi,
The moon this morning was a descending crescent. Around midnight it was an "upside down" crescent, around 6am I noticed it was back it its "upright" position.
I understand that it's the sun reflecting, but how often does it happen? Evert night? If not then why?

[Jonathan-Joe]

The moon itself is dark, one half of it is illuminated by the sun, we see only part of the visible side. The part we see changes as the moon revolves around the earth and as the earth / moon system revolve around the sun. But the planes of these revolutions are at angles to each other so to we have a problem in three dimensions. There are articles in the web to explain and illustrate this - here's one http://starchild.gsfc.nasa.gov/docs/StarChild/questions/question43.html Hope it helps.

[mibn2cweus]

The Moon appears as a crescent shape when it is nearer to conjuction (less than half full or 90 degrees from the Sun) than opposition with the Sun.

Regardless of the Moon's apparent orientation to the nearest horizon at any given time, the 'tips' of a crescent moon always point away from the Sun.

[scowie]

The moon rose in the east at about half past midnight and it would obviously have been it's bottom edge that was lit (the side pointing at the sun). After arcing across the sky, at 6am it was at about it's highest point. It would have been closest to the southern horizon so that would be your reference point, i.e. you'd consider down to be towards the south, but since the lit side would be pointing further to the east now (where the sun would be rising from) you may get the impression that the moon had rotated, but really it's your frame of reference that has changed.

If you saw it well after midnight, then again at around 6am, i'd say you need to get more sleep! ;)

[scowie]

Actually, that was last night when it rose at 0:30-ish, it was more like 11:30-ish on Friday night. Been checking using the free Stellarium - I recommend it :)

You should still get more sleep though! ;)

[scowie]

...Thursday night I meant. (the lack of editing here really is a pain in the ***!)

[Old_Geezer]

I think that link proves how weird it is to see a crescent moon at all. When the moon is at it's height in the night sky, if it has avoided the shadow of the Earth, then it is seen as a full moon from the Earth. As it nears the horizon one sees less and less lit up until at the horizon it is a half moon. But surely this means it has to dip below the horizon where we don't see it for there to be a crescent ? So we ought not be able to see crescent moons except in the daytime when the light of the sun ensures we don't see the moon at all. It's all magic I tell you. The Gods put the crescent ones up when you aren't watching them. They only exist when you choose to observe them.