Why do I have a crescent moon next to the time on my iphone?

[Narjan]

And how do I get rid of it? -__-'
Thank you.

[Ryu]

It's Do not disturb mode. You don't get notifications for missed calls and such.

Just go to settings and turn it off

[That.One.Guy]

That means your iPhone is in "Do Not Disturb" mode which will cause you to not be alerted when you get a notification (such as a phone call, message, Facebook/twitter notification).

To turn this on or off, go to:

Settings < Do Not Disturb < "ON" or "OFF"

You can also edit the times you want "Do Not Disturb" to be on by going to

Settings < Notifications < Do Not Disturb

Hope this helps

[ScσττRΛSC³]

That's the symbol for Do Not Disturb, a new iOS 6 feature that does what the name describes. Disables notifications/calls during the time it is active.

The setting to turn it off is easily found in the Settings app.