A light look at celestial bodies

David Levy is known to the public as co-discoverer of Comet Shoemaker-Levy, which crashed spectacularly into Jupiter in 1994. But how does somebody find a comet?

This book will tell you. But it is also the tale of a life in science that has involved the author in appreciating the beauty of the universe as well as enhancing our knowledge of it. It begins with the youthful Levy's first encounters with the sky. He began comet-hunting on December 17, 1965 (his records must fill yards of shelving), and has since discovered 21. But this book contains almost no information about comets.

Instead, the emphasis is on the 383 "Levy objects" he has noted in the sky in the course of his comet-seeking. In drawing up this catalogue, Levy follows consciously in the footsteps of Charles Messier, who in 18th-century France recorded 110 objects in the sky that might fool the unwary into thinking they had found a comet.

Levy succeeds in three big tasks in this book. One is to tell us his own remarkable life story as a scientist. In the process, we meet a catalogue of other notable characters from the Shoemakers to Clyde Tombaugh, the discoverer of Pluto. Another is to give anyone interested the information they need to get out a telescope and find the Levy objects. And the third is to tell us what they mean. Levy describes his objects in order of their distance from the Earth. He also sweetens the dish with a vast array of literary references to the sky that are in themselves worth the price of the book.

One objection to his list is that some of its members are mere "asterisms", chance star patterns that look interesting but mean nothing. The book itself is also confusing, with a range of overlapping lists that need rationalising for a second edition. And its proofreaders were not completely awake. On one page the term "radio velocity" appears just a few lines away from radial velocity, the correct version. Elsewhere, a picture appears with an obviously wrong caption.

But when he gets into his stride, Levy explains the sky beautifully. In a few paragraphs, he describes how stars vary in brightness, how they belong to clusters or to streams hurtling through space, and how they form. We now know that many of the shining patches in space that Messier saw are nurseries where star formation is going on today. Later, Levy shows us the other end of the life of a star in the shape of planetary nebulae. These are the gas clouds formed by exploding stars and are among the most pleasing objects in the sky.

As the view widens, Levy looks at star clusters and how they have been used to determine the size of the universe, and at whole galaxies and the shapes they take on. Finally, we get to the first galaxies to form in the early universe. We can see them because of the time their light has taken to get to us, but we know that they ceased to exist billions of years ago.

This book has a title as modest as its author, but its charming approach to such important material makes it one for anyone who loves the night sky.

Martin Ince is contributing editor, The Times Higher .