Indeed, impact cratering may have been the dominant geological process on Earth during the Late Heavy Bombardment, an epoch 4 b.y. ago recorded by the saturated craters of the lunar highlands. Such cratering may have established the boundary conditions from which the modern tectonic style of our planet developed. It should be even less debatable that the continuing rain of projectiles, with effects mediated by Earth's atmosphere, must occasionally cause havoc to our planet's fragile ecosphere. Given the possibility, on a time scale of aeons, that a giant comet might even sterilize our planet, it is hardly inevitable that life has survived for as long as it has. However, many paleontologists and evolutionary biologists still steadfastly resist even the possibility that the sudden, dramatic changes in the diversity of species in the geological record could be due to impact-generated upsets to ecological stability.
Steel is well qualified to write such a book.
He is an expert on meteor streams and, for several years, he has been involved in the astronomical search for asteroids and comets, using the Anglo-Australian Observatory. He is one of the most visible and enthusiastic explicators of science on popular television Down Under and, as this book exemplifies, he is a gifted writer. I will return to these technical issues later. First, however, since the volume is aimed at a lay audience, I will address whether this book is, in fact, a good popularization of science. Reading the first 60 pages, or so, I thought that it might be.