How to adjust my Nikon D40 Shutter Speed beyond 30 seconds?

I want to set my D40 up on a tripod to do night photography of star trails. When I put the D40 in Manual mode, adjust my aperture and ISO, I can only adjust my shutter speed up to 30 seconds. Anything past and it says "BULB." How can I adjust my camera's shutter to remain open for 30 minutes or even an hour?

NOTE: I'm currently adjusting my settings while indoors before I take it outside.

30 seconds is the longest timed shutter speed an any dSLR camera.

To take shots using longer shutter speeds, you will need to hold the shutter down with the camera in the bulb mode and use a stop watch to keep time.

It is usually better to use a remote shutter release and hold it open remotely to prevent camera movement which will blur the images

Bulb is what you want. When in BULB mode, the shutter opens and the sensor records an image until you hit the shutter button again.So, once the camera is on your tripod, turn the camera to bulb, turn OFF VR on the lens, hit the shutter button and when you want to stop the exposure, hit th e button again