Multiple long exposures for astrophotography?

I'm wondering if anyone has experience with the Nikon D5000's menus. I'd like to take several hundred 30-second exposures over the course of a few hours, but I can't *** figure out for my life how to put the camera into this mode.

I figured out how to use bulb mode and did an hour-long exposure, but I'd really like to try compiling several hundred exposures to (hopefully) minimize noise.

All I want to do is press the shutter once and have the camera take 30-second exposures continuously.

Added (1). The interval timer is indeed the way to do this. I was just setting the exposure time / interval time as the same number, so I was telling it to do something impossible.

Choosing a 30-second exposure and choosing 32+ second interval is the way to go.

Are you trying to use what is called an interval timer to do this?

http://support.nikonusa.com/...accessible

I have such a timer on my D300 and D3, but you will have to call Nikon to see if your D5000 has the feature

You need a remote intervalometer - the D5000 doesn't have one built in I don't think (check your manual).

My D300 has one - this was set up to take a 30sec exposures, 10 seconds apart and it's composed of 129 images stacked using Startrails software;

software link (free);
http://www.startrails.de/html/software.html