RAIN OF IRON AND ICE

Dr. Lewis is Professor of Planetary Sciences at the Lunar and Planetary Laboratory in Tucson, AZ and codirector of the NASA/University of Arizona Space Engineering Research Center. He has been studying the promise and perils of asteroids for many years.

This book is devoted to the latter aspect of asteroids. We are only beginning to understand the nature and magnitude of the problem of asteroid impacts. Because the importance of this problem is not widely recognized, Dr. Lewis devotes much of this book to history. He has examined centuries' worth of journals, often translating from French or other European languages, to document how apocryphal tales, written accounts, and even geological evidence have generally been dismissed by authorities.

Although meteorites have fallen, and been recovered in, many lands throughout history, it was not until this century — and then only after significant opposition — that most scientists accepted that large craters on Earth were caused by impacts, rather than volcanoes. The fact that bodies capable of causing similar craters are still out there, and that the possibility of global devastation still exists, was an even harder sell. In 1994, Comet Shoemaker-Levy 9 slammed into Jupiter; this woke a lot of people up.

Yet the problem is still under-addressed. Dr. Lewis estimates that to detect, track and catalogue most of the near-Earth asteroids down to 250 m diameter, a network of telescopes costing $300 million over 20 years would be required. The U.S. Congress funded one new telescope for this purpose in 1994, and its staff has more recently been cut back. At present, we know only a small fraction of this asteroid population well enough to predict whether or not they will strike Earth. So we are nowhere near identifying the threats, let alone making progress toward being able to do something about them.

In addition to historical accounts that cover a range of impacts — everything from the 1908 Tunguska event down to falls that killed a single horse, or burned down a stable — Dr. Lewis describes the impact of the larger bodies that we know from the cratering records of this and other planets are capable of killing billions of people. It is a multi-faceted threat, involving factors including the following:

Obviously, not all of these things happen for every impact. And much depends on the size of the body, its speed, its composition, and where it hits. But the potential for disaster is there, and we should prepare. This book is a well-reasoned, non-alarmist argument for how much and what kind of preparation is warranted.

As I mentioned, Dr. Lewis reviewed an astounding volume of material to find the incidents he lists here. His secondary purpose, to discredit the shortsightedness of authorities regarding meteorite impacts, is more than accomplished. Indeed, it strikes me as overdone by chapter 13; I think the point has been made by then. I also felt chapter 13 came across as a bit smug. Yet it is worthwhile to have all these incidents collected in one place.

As for typos, I did find a few. On page 89, the book refers to Arthur C. "Clark," just after Clarke's name is spelled correctly twice. On page 107 is a reference to Ernst J. Opik publishing poetry in Irish; I assume this means Irish Gaelic. And page 174 has the statement, "...it makes little or no difference whether one person is killed by meteorites each century, or one hundred people are killed each year." I believe the positions of the words "century" and "year" should be reversed.

There is no bibliography per se; most sources are given in the text. But Dr. Lewis does provide a few suggestions for further reading at the end of the book. There is an index, and the paperback edition includes an afterword with a few new asteroid appearances.

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This page was last modified on 11 July 2014.