If you like big numbers, space is the place to be. In our galaxy, 100, 000 light years across, are 500,000 stars and a subject, astronomy, made up of millions of loosely-connected facts. Fortunately, only some are needed for the half-dozen sentences that make up the curriculum.

For children, astronomy has plenty of mileage. For science teachers, the opportunities for practical work are scarce. So when you can’t reach for the stars, you’ll have to reach for your CD-Rom.

Dorling Kindersley may be late in adding a space title to its range, but it has got something headed for success. Need a display of the orbits of the planets? The phases of the moon? The birth of a star? It is all here and, as we’ve come to expect with CD-Rom, much of this is explained, illustrated and animated. There are sections about cosmology, the birth of the universe and space exploration. You can find the background to the technology of space exploration - gravity, rockets and life in space. There’s plenty that most teenagers could handle, and, unlike with past DK titles, they can copy the pictures and text.

You click on the “space console” to find all this information, and you can also use it to enter the “star dome”. This excellent feature picks up today’s date and time to show you the positions of the sun, moon, planets and constellations as they are in the sky right now. You see them as labelled blobs that move as time passes, or as you fast forward by the month, day, or minute. Remembering there would be a solar eclipse in October, I surprised myself by pin-pointing the event down to Saturday, October 12, after lunch.

There is lighter stuff too: a quiz that isn’t punitive and a couple of games - assembling the stages of a rocket and adjusting the thrust for a moon landing - from which you could learn.

This DK title is good. There are millions of facts and lots of see-also buttons, offering to help make connections between them. It seems almost unfair to compare it with Earth and Universe, a title expressly designed for schools, which had a much lower budget.

To its credit, it has classroom worksheets, a teacher’s guideP and even words about the tides that you can copy and re-use.

It also has a very relevant section collecting together observations, such as the movement of the sun in the sky, and explaining them using animation.

But otherwise the approach is so dry that it’s really only suitable for children who desperately want to know. That there is no background music and no graphic effects isn’t the issue: it’s more to do with a sense of enjoyment and atmosphere. Even with a space CD-Rom, learning is hard in this vacuum.