This is Waltham’s first excursion into popular science, and the topic could neither be more ambitious, profound nor important. What circumstances conspire to give rise to a functioning biosphere, a comparatively stable surface temperature (OK, there were a few major ice house and hot-house Earth events in between), and intelligent life?
What is our best guess at the number of habitable worlds in the known universe (or multiverse, if you take that view)? How has the greenhouse effect been moderated throughout much of Earth’s history, and what are the relative roles of continental weathering capturing atmospheric CO2
versus the rise of eukaryotes and complex life?
The prologue lays the thesis bare to see: consider Earth, a habitable haven of life, and its ill-fated imaginary twin, Nemesis. After an auspicious start, when dinosaurs ruled the Earth and dragons breathed fire on Nemesis, their parallel paths diverged. For a number of reasons, which we learn much later in the book, the death of the biosphere on Nemesis was predicated by her moon being much too large. Our moon is just right, so the book argues, and this ‘goldilocks’ view lies simmering beneath the surface throughout almost all of its chapters, emerging more fully in the last.
For a number of very sober reasons, the author distances himself from the Gaia view, while remaining very respectful to all who try to address the serious question of why we are here. Waltham points out that a number of key ingredients to life on Earth - notably a comparatively stable Earth-Moon pairing- are simply out of the influence of Earth-borne and Earth-inhabiting life. The book is never so technical as to be unintelligible to those who are not astrobiologists, but may be a little hard to grasp for those not very conversant with the Earth sciences, astronomy or physics.
It’s a great read overall, and I shall never look at the incorrectly illuminated half moon in my niece’s Peppa Pig book in quite the same way again. I will leave it to the Fellowship to find out why.
Reviewed by Daniel LeHeron
LUCKY PLANET: WHY EARTH IS EXCEPTIONAL - AND WHAT THAT MEANS FOR LIFE IN THE UNIVERSE by DAVID WALTHAM
2014. ISBN: 978-1848316560 224pp. Published by: Icon Books. List Price: £14.99 W: www.iconbooks.com/blog/title/lucky-planet/