Ever seen a comet in your bedroom?

Twinkle twinkle little star, I know exactly what you are. You are staring at a screen full of stars, planets and asteroids. Click on one, and a few moments later its name and vital statistics appear. Most of them are meaningless to the astronomically illiterate, but they are impressively complete nonetheless.

If you are expecting this "multimedia astronomy" guide to be a relative of Red Dwarf or to have spectacular Star Wars effects, you will be sorely disappointed. But if you want to spend hours getting your head round astronomy, it is the one for you. As someone who has never been able to get excited by the stars (mainly because they are such a heck of a long way away) I found it utterly absorbing.

Do not, however, give it to anyone who is not prepared to put in time working out how to get the most from it - the universe is a complicated place, so this disk has to be as well.

You can start off simply enough with a series of animated guides to the Milky Way or Orbits in the Solar System. Despite Hannah Gordon's soothing commentary, this felt a bit like going back to school. The real fun starts in the main program, which can show the view from any point in the solar system any time over a 15,000-year span.

You can even, as the publicity says, ride Halleys Comet, although if you expect to be whooshed off your seat, you will be disappointed: you simply see the star patterns changing.

The most obvious experiment is to set up the "virtual sky" as it is now, and then go outside to check. I did, and it worked: Orion was where it was supposed to be. But you need a good deal of practice to get this right. As well as adjusting your position, time, direction and viewing angle, you need to select the objects you want to see (stars, planets, comets etc) and the brightness, so that you are seeing the same things as the screen. In a big city you can see less than you would in the countryside, and you need to compensate for this.

I was frustrated at first because I could not get the moon appearing as I saw it: it was just another tiny spot. Then I played with the "zoom" button and it appeared (in the same phase as my diary said it should, so it must be right). That is the joy of this disk - you want to on playing until you crack a problem.

There is a great deal of technical data that left me baffled (I have no idea whether it would be useful to an expert). There are also plenty of spectacular still photos and some video clips: some are graphical interpretations, others real film such as moon walks. Christmas tip: give this disk to your teenager, then when he or she discards it in disappointment at the lack of action, grab it for yourself.

RedShift 2. PC and Mac. pounds 49.99. Maris Multimedia, Tel 0171 490 2333.

DAVID BOWEN