Worlds without End - Chris Impey ****

I was a bit wary when I saw this book because there seem to be almost as many books about exoplanets and astrobiology as there have been planets discovered around new stars. However, it proved a pleasant surprise, as a result of the approach that Chris Impey has taken, and I found it an enjoyable read.

In four sections, Impey takes us through the search for exoplanets, the potential habitability of different worlds, from gas giants to Earth clones, what can be done to search for the existence of life in other planetary systems, and space exploration. The last section, to be honest, really is unnecessary - it's a distinctly different topic covered better in other titles, and I would have been happy to have had more on the earlier subjects. But in the first three sections, the great thing about Impey's approach is the way he drives the discoveries and ideas (there aren't, of course, any astrobiology discoveries per se as it is all theoretical so far) from the individuals involved.

To pick out two examples, the 'Doppler wobble' chapter begins with the sounds of corks popping in 1995 as Swiss astronomers in the south of France celebrated the uncovering of data that provided the first confirmation of an exoplanet, despite, as Impey comments 'using a telescope not big enough to be in the top seventy worldwide.' (It wasn't the first detection, but the first time it became pretty much definitive.) In a later chapter we see the Drake equation being first written in 1961. This very guesswork so-called equation is perhaps given rather more coverage than it deserves as it tells us nothing: but the story is interesting, and, unlike some, Impey at least acknowledges the degree of uncertainty that makes it pretty much useless, except as a way of reminding us of how difficult it is have any idea of how common intelligent life might be in our galaxy.

I do have one big complaint - like many scientists writing popular science, Impey is fine when he sticks to the science content, but can go astray when he gets into history. He commits the worst example of Brunoitis I've seen in a long while. Giordano Bruno (who funnily enough I've just reviewed in his fictional role as a detective) was a sixteenth century Italian mystic who famously commented on the stars being suns with peopled planets and who was burned as a heretic. Impey makes the two classic mistakes. Firstly, he makes it sound as if Bruno's cosmological ideas were original - but they were taken from the much earlier Nicholas of Cusa. The second is to suggest that Bruno was martyred for his science. In reality, Bruno's primary heresies were all conventional religious ones (notably, Nicholas was not persecuted just for having these ideas - in fact, he was made a cardinal). Of course Bruno's persecution was still horrible - but Bruno didn't die because of his very waffly cosmological musing.

As long as you hold your breath and get past Bruno (who is much more entertaining as a fictional character) though, this book gives a great picture of the personalities involved in exoplanet detection and astrobiology, and simple yet effective descriptions of the science that lies behind the discoveries and ideas.

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Review by Brian Clegg - See all Brian's online articles or subscribe to a weekly email free here