The Pale Blue Data Point - Jon Willis *****

The title tells you exactly what this book is about, if a little cryptically. The ‘pale blue dot’ is our own planet Earth, seen from a cosmic viewpoint – and, as far as astrobiology is concerned, it’s actually the only data point we have, counterbalancing centuries of theorising, speculation and fantasy. The book’s scope is summarised in less poetic terms in the subtitle: ‘An Earth-Based Perspective on the Search for Alien Life’. Over the years we’ve reviewed quite a few books about astrobiology on this site, but while many of these have made the point that useful things can be learned about the subject by studying our own planet, it’s generally only been a few tantalising comments in passing. So a whole book on this topic is long overdue and very welcome.

Having been interested in space and astronomy for over 50 years now, it irritates me how some misconceptions just refuse to go away, generation after generation. One example is the notion that the Earth and space are two completely separate things, and that any suggestion of a connection between the two lies in the realm of UFOs and science fiction. That’s nonsense, of course – there’s no atom of matter on our planet that didn’t originate in some other part of the galaxy, and we’re now pretty sure there are millions of other planets having a similar composition, structure and environment. In astronomical terms, the Earth really is what the book’s title says – a data point – and there’s no reason to suppose that’s not true from an astrobiological point of view too.The great thing about studying the Earth, as opposed to other planets, is that it’s something we can all do. Jon Willis is a professor of astronomy – but astronomy is a wide field, and his day job has nothing to do with astrobiology. It is really just his hobby, and large parts of the book have a distinct (and enviable, for someone of my age and sedentary nature) element of ‘scientific tourism’, to use Willis’s own phrase. He doesn’t just tell us how we can learn about the moons of Jupiter – or ancient Mars, or the formation of planetary systems, or communicating with extraterrestrials – here on Earth, he actually goes out and does it himself.

Close to his home on the west coast of Canada, we find Willis doing a stint as a science communicator – broadcasting to schools and museums – on board a research vessel operating deep-sea submersibles. The astrobiological interest here lies in the thriving ecosystems surrounding hydrothermal vents, which may possibly have a counterpart in the ice-covered ocean of Jupiter’s moon Europa. There’s a slight catch, which I don’t think I’d appreciated before, in that all the easily visible lifeforms around deep-sea vents are actually dependent on Earth’s global ecosystem – including photosynthesising algae up near the sea surface – and hence not something that’s likely to be found on Europa. On the other hand, microscopic chemosynthetic bacteria, which are also present in Earth’s hydrothermal vents, just might be.

For Mars, Willis travels to Australia to examine stromatolites – colonies of very primitive organisms called cyanobacteria – both in living form in Shark Bay and as ancient fossils in the Pilbara Craton. Way back when the latter were formed, Mars was almost a twin of Earth in terms of climate and surface environment, so it’s not unreasonable to imagine that stromatolites might have arisen there too. Another field trip sees Willis on a meteorite hunting expedition in Morocco, eventually coming away with quite a haul – although he admits that, apart from a few tiny fragments that he picked up from the desert floor, these were mostly shop purchases. Astrophysically, meteorites are important because they tell us about the composition of the very young solar system, soon after its formation – and they’re important for life on Earth, too, because they were the likely source of at least some of our water.

The last chapter sees Willis swimming with a group of dolphins off the Bahamas, as he accompanies a team of scientists studying the way these animals communicate with each other. The significance for astrobiology is that dolphins have an incredibly wide and complex range of vocalisations – whistles, clicks and squawks – and yet even today we have no idea what they’re saying to each other, beyond recognising the names, or call-signs, of individual dolphins. If they really do have their own language, then we’re nowhere near cracking it – which doesn’t say much for our ability to decode any genuinely alien message we might receive in future.

Despite the fact that it hardly ever leaves Earth, I found this the most fascinating and eye-opening book about extraterrestrial life that I’ve read for a long time. [Ed: It's an interesting contrast with Willis's earlier, more conventional astrobiology book.] The word astrobiology suggests the intersection of two completely different branches of science, astronomy and biology – but Willis’s approach makes it clear that many other disciplines are important as well, including chemistry, geology, palaeontology, oceanography and even linguistics. In fact, if it’s relevant to the study of life on Earth – still our one and only data point – then it’s relevant to the search for life elsewhere too.

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