Poets with stars in their eyes

The stars of the night sky lie distributed in the three- dimensional space near the sun. Our perspective forms them into two-dimensional arrangements. These "constellations" have a significance only in human imagination - but they are among the earliest works of the imagination.

The earliest surviving description of the constellations is by Aratus (315-250 bc). His work's central position in western astronomical culture is in part due to the supposition that St Luke quotes it in the Acts of the Apostles 17:28 ("as certain of your own poets have said . . ."). Aratus's work is itself based on research by Eudoxus (409-356 bc) carried out among the ancient books in the libraries in Alexandria, but it is clear the constellations originated before even these lost records.

Some credit Chiron, the Centaur, with the invention of the constellations, arranged as mythological figures, gods and goddesses (he "mark'd the sphere celestial" - John Dyer, 1757). There is internal astronomical evidence ("precession") in the tilts of the constellations which implies that the arrangement of the northern constellations became fixed in 2800 bc, plus or minus 300 years, at latitude 36 degrees. This corresponds to the civilisations in Mesopotamia, from where the constellation figures diffused into the Mediterranean.

Some individual constellations might go back further in time. Ursa Major, the Great Bear, is readily recognisable, but does not look the least like a bear, more like a ladle (its modern American name is Big Dipper) or a sculptor's pick (its Egyptian name). It is called the Bear by the North American indians and the inhabitants of Siberia, who could be expected to be more familiar with bears than Greeks and Romans, from whom our name for the constellation derives. This identification seems to have migrated into the south from northern Asian lands. Moreover, since the inhabitants of Siberia and the North American indians separated across a land bridge broken by the Bering Strait 9000 years ago, it seems that this particular constellation had its origin before then.

The present 48 northern constellations are mostly the constellations of classical allusions, redefined by the International Astronomical Union in 1928. The 40 southern constellations lie outside classical astrology, and include the Telescope, the Pendulum Clock and the Chemical Furnace. They are ambiguous symbols, simultaneously familiar as stars and unfamiliar as constellations.

They are both new and eternal, disturbing features of the strange lands that the southern skies overhang, bringing to mind adventure and imperialism ("clearer flames glow round the frozen pole" - Alexander Pope, 1713; "strange-eyed constellations reign" - Thomas Hardy, 1902).

Michael Bakich is a planetarium director. His book lists the constellations, including those now extinct, their non-traditional mythological references (including reference to the Ice Cream Cone!) and interesting facts about each. There are both modern maps and ancient maps of each constellation, which in the cases of the newer ones show their first depictions.

The book gives data about the brightest stars within the constellations, and the nearest stars. The book has some novel ideas for the presentation of a wealth of unusual material and I found no mistakes. It is not a bedside book for browsing. It is a work to reside on a shelf for reference, mostly for amateur astronomers' use, but also for anyone with an interest in the stars.

Paul Murdin is the head of astronomy, Particle Physics and Astronomy Research Council.