Which lens to use with mny nikon d3100 for night sky photography?

Hi, i have recently purchased a nikon d3100 with a nikon DX AF-S nikkor 18-55mm VR lens which i'm very happy with. I'm at the stage where i would love to start shooting the sky at night, stars and moon.
my question is would i benefit form purchasing a different lens or a conversion lens and if so which lens would you recommend. Also what would be a good setting to have my camera on with my current lens.

The biggest aperture you can get. Better idea would be to mount it on a telescope. You don't need special lenses if you can lock the shutter open for several seconds. A telescope is the best bet though, for lunar work it doesn't even need to be a big one

The kit lens that you already have can be used for night sky photography. You will need a tripod to steady the camera though when you use Bulb as the shutter setting. I'm not sure with Nikon dSLRs but you may also need a remote shutter release