Space cadets out there, rejoice. And no, we're not talking about bong-toting hippies or avid Star Trek anoraks, but those disciples of the night sky who like to spend the wee hours gazing up into space through a small white tube filled with mirrors. The reason for this rejuvenating chorus of hallelujahs? Nothing less than the arrival of the latest version of Starry Night Backyard.

Starry Night Backyard 4 is aimed at the more serious amateur astronomers out there, although those newer to the hobby will still find it very useful, particularly as it comes with an interesting 200 page companion book which explains many basic star-gazing concepts - top marks to the suppliers for the inclusion of this worthy tome.

The main section of the program is, of course, the actual sky map. This is one serious piece of intergalactic cartography, spanning some 20,000 light years and documenting 2.5 million stars, not to mention comets, asteroids and other deep space phenomena such as nebulae. Not only can you view any location in this vast expanse of space, zooming in and out at will, but you can also travel in time to see what the universe looks like at any point between 4700 BC and 9999 AD.

A search option lets you locate any heavenly body and you can also observe the night sky exactly as it appears when viewed from any city or location in the world, complete with constellations and suchlike marked out. The level of detail and presentation of the map is of a good quality, although at times descriptive text can be poorly placed and coloured so it's difficult to read. The space map updates can also be a little jerky on lesser-specced (below 1 GHz) machines, so be warned.

Reasonably detailed descriptions are provided for every stellar object and the program is very thorough, with lots of smart little touches such as the ability to set light pollution levels if you're in a big city. What's most exciting about Starry Night Backyard 4, however, is the excellent observation planner. This gives you a minute-by-minute readout of what you can expect to see during the course of any night depending on your location, so you know exactly where to point your telescope when a particular comet or planet becomes visible, or when you might catch a glimpse of the ancient remnants of a supernova.

Starry Night Backyard 4 also features a second CD-ROM which contains over 90 minutes of video on a range of astronomical topics. These are high quality and informative mini-films. The only real downside to this package is that it's a tad on the pricey side.

As the old cliché goes, you pays your money and takes your choice. Starry Night Backyard 4 runs close to this rule. It's an excellent, well-featured product complete with many useful extras such as videos and a useful book, but you do have to fork out considerably for the privilege of owning it, compared with other reference titles. There are minor presentation issues with the program, but nothing too off-putting.