SOLAR SYSTEM EXPLORER SPACE STATION SIMULATOR. Maris Multimedia CD-Roms for Multimedia PCMacPounds 39.99. Age 14+.

DISCOVERY CHANNEL BEYOND PLANET EARTH. BMG Interactive CD-Rom for Multimedia PC, Pounds 19.99. Age 15+.

THE UNIVERSE BEYOND. Mindscape CD-Rom for Multimedia PC, Pounds 34.99. Age 16-adult.

All available from retail outlets

Picking a CD-Rom about astronomy from the hundreds that can be found in orbit is getting more difficult, says Roger Frost

Isn’t it amazing? Every time the moon does a spin round the earth - that’s every 28 days - a publisher somewhere on the planet launches yet another shiny CD-Rom about astronomy. You are spoilt for choice, so choosing a favourite, from the hundreds currently in orbit, is not easy.

In this latest bunch, there’s something unique and desirable about each, and picking one is as hard as saying which moon you like best. Take Nine Worlds, perhaps the best looking of them. It’s led by Patrick (Star Trek) Stewart whose dramatic, powerful voice takes you on a planetary tour. It adds more drama with music from Holst’s The Planets and fly-over animation that’s almost real.

Pupil-friendly features, of which there are few, include probes to measure the size, orbits and temperature of each planet. A “holiday planner” is a good way of setting out the facts - it tells how long your trip will take, what the weather is like and what your weight would be. That the disc also takes you to exclusive places on the Internet, places to chat and read today’s news ought to clinch the deal.

Nice it is, but the bottom line is that it’s mostly for teachers.

OK, how about the idea of actually piloting a space craft? In Solar System Explorer, from the makers of Redshift, you can read about the countless expeditions into space and “walk around” the space craft they used. Better still, you can pilot the space ship to relive the experience. You can join Apollo’s trip to the moon, or Viking’s trip to Mars, and many more. You can speed things up with a time-warp feature, or while away years in the ship’s library swotting up on space facts.

And, as you watch from the bridge, you’ll see the Earth revolving under you, see the heavens, pick out the stars - they’re labelled for you, too. When you realise, as young people may, that you’re in the real “model”, the idea becomes awesome. They will need guidance - the harder bit is finding the lesson slot to use it: it needs more than any lesson allows.

In another title, Space Station Simulator, again from the same folk, you can assemble the space station which is due for launch in 2003. As the disc explains, it’s an international project in progress, but here you can get ahead of schedule and fit it with as many robot arms, solar panels and space labs as you like. You can steer the thing in earth orbit and, with that awesome word in mind, you can even walk around inside the thing. If you want to find out how the real project is going, an Internet button can bring you the latest news via the World Wide Web.

The Universe Beyond is another with an impressive look to it. It’s a blend of astronomy, myth and mystery, all told in a rich, wondrous style. There are some excellent 3D “fly-throughs” - short clips about the Big Bang, falling into a black hole, and a zoom through the universe. Nice though these are, this is for enthusiasts and for those who like their science mixed with culture and history.

Set beside the lovely gloss, Beyond Planet Earth, appears average. It features around 40 film clips from NASA and, with a few hundred photos, it creates a sort of documentary about the planets and the stars. Like much of the rest here, it’s interesting and you can find what you need with a search button. And, like the rest here, it’s stimulus material for the library but a good selection for the fans.

True, there are no stars here. What’s wanted is something that guarantees a learning result, but I’ll admit to wanting the moon on a stick. No doubt it will go on revolving and the heavens will deliver.