Is it possible to modify my Nikon d5000 to take exposures longer than 30 seconds?

I have a Nikon d5000 and I want to use it for astro-photography.
I know some people are modifying their cameras to allow for IR light to pass through, but I want to use a longer exposure instead, or possibly in parallel.

Is there a way for me to make the camera take an exposure longer than the 30second maximum that it comes with?

Do you still have the Owners Manual which is included with the camera for a reason? If so than why haven't you picked up and started reading the Owners Manual yet?

Try Looking on Page 86 of the Owners Manual
http://www.nikonusa.com/...000_en.pdf

Look up bulb mode in your manual.

Yes, in bulb mode. In that mode, the shutter will stay open as long as the shutter release is held. You should have a remote shutter release connected to the camera (or use the wireless one) on a tripod.

Do what dead said. My mom has that camera and I think she can!

There's a bulb mode, which allows the shutter to be open as long as the buttn is depressed.
However if you are looking for a feature that will allow you to hit a button then walk away, I don't think it will have one. I have never met a photographer who has modified it like you say.
Mainly because an image will become very noisy after that long.