Customer Reviews

Fire on Earth: Doomsday, Dinosaurs, and Humankind

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People have trouble with long time scales. We can't experience anything longer than the time we live, and have to resort to extrapolation and imaginative analogies. But happenings on very large time scales--geological and astronomical time scales--aren't required to accord with human experience. The earth looks stable to us because as long as we can remember, it has remained relatively constant. Yet the geological record proves to us that the earth has at times been scarred by impacts from asteroids and other space debris.

John and Mary Gribbin examine this matter and its consequences for the human race in *Fire on Earth*. The book looks at some of the physics and history behind collisions on earth, and the descriptions of the effects of the collisions make nuclear holocaust seem like a dribble in a pond.

Yet, from the very beginning of the book, errors make reading a distracting act indeed. Another reader has already pointed out the missing slash in the equation for kinetic energy, changing 1/2 to 12. There are more inconsistencies: the mass of the famed Tunguska object is given variously as 100,000 tonnes or 1,000,000 tonnes, and yet later in the book, an object that is "substantially larger" than the Tunguska object has an estimated mass of 1,000 tonnes. Huh?

Similar errors dot the book. A more serious weakness has to do with the end of the book. After describing the geological, ecological, and meteorological consequences of an impact, the Gribbins attempt to explain wars and social change as the indirect results of comet or asteroid impacts.

This doesn't ring true, or at the very least, the Gribbins don't make a very convincing case for it. This penultimate chapter reminds one of lawyers arguing a case, where circumstances are very carefully assembled to support an assertion, circumstances that give the impression of strength, but that fall over under the slightest breath of opposition.

This book isn't intended to be an in-depth, scientific examination of impacts; the Gribbins wrote a popular book on an increasingly popular subject. But careless proofreading and a runaway imagination mar the book. Enough information is here to satisfy many; but for a more objective survey of the same subject, consider Gerrit Verschuur's *Impact*, or even Carl Sagan's *Comet*. The Gribbins have the style, as evinced by the long list of popular science books they've written, but this one just doesn't measure up.

One thing very specifically bothered me about "Fire On Earth". It is a typo that should never have gotten by the astute eyes of editorial staff at St. Martin's Press. The equation for kinetic energy is given as the product of mass and velocity (square), multiplied by 12. A layman trying to create his own rock of doom will come up with an blast energy that is off by a factor of 24.

That particular typo notwithstanding, "Fire On Earth" should break no new ground for serious students of cosmic impact. Much of the book is a recounting of information already available in other, more authoritative texts. The one redeeming feature of the book is its easy-to-read style, which allows the reader to quickly grasp the scope of the impact threat without trying to muddle through a lot of technical jargon.

Those desiring to read a more serious treatment of the threat of asteroids and comets should check out "Rain of Iron and Ice" by John S. Lewis and "T-Rex and the Crater of Doom" by Walter Alvarez.

A previous reader comments about missing slashes in formulas and excessive or lesser number of zeros in quantitative estimations of for example the Tunguska impactor on this book and it is true that this type of mistakes are common in the text but I found more serious errors in the following pages(these refer to the hardcover edition of the book): a)On page 32: "standard dating techniques involving measurements of radiactive argon in the rocks showed that the (Manson)crater had formed exactly 65 Myr ago". False. We know since 1993 that a careful application of this same technique to this crater reveal "exactly" 73.8 Myr for this formation. b)On the same page:"...geologists have also found another crater (Popigai)65 Myr old". Not true. Geologically Popigai is around 35 Myr old. c)Errors (a) and (b) conduce to the statement on page 33: "...three pieces of interplanetary debris...strike simultaneosly in Yucatan, Iowa and northern Siberia". Similar mistakes to (a) and (b) are repeated on page 133. d)On page 57:"...it was certainly(the explosive power of the Sikhote-Alin impact) at least 100,000 Kilotonnes". False. A minimun of at least 100 kilotonnes is enough for explain the characteristics observed of this impact. e)On the same page:"...in April 1972, came a genuine close encounter(the Montana fireball).False.The genuine Montana fireball close encounter came on August 10, 1972. f)On page 69:"Venus,..spins.. with each day lasting a year".Not true.Venus spins with each day lasting 243.01 Earth's days and each venusian year lasting 224.701 Earth's days. These are mistakes that I am aware of and do not diminish any other virtues that readers may find in the book.

John and Mary Gribbin has written an interesting work entitled "Fire On Earth," where the authors discussed the cosmic hazards and also focuses on the extinctions, Tunguska event, as well the works of Clube and Napier on "Cosmic Winters" and the work of Muller on "Nemesis" theory. This book contains roughly 260 pages and ten chapters.

From this book, I was certainly interested in the authors' discussion of the works of Clube and Napier in the chapter entitled "Cosmic Winters" and Muller's work briefly in the chapter entitled "Cycles of Doom." They also bring in a discussion of Oort clouds where at one point they stated that "a disturbance of the Opik-Oort cloud leads...to an increased chance of cometary collisions with the inner planets, probably producing repeated impacts on Earth" (p. 169), which is important to know. In the end, the authors attempted the proposal of a SpaceWatch project to provide a protection against cosmic impacts and urged the scientific community to take cosmic threat seriously.

Overall, this book is not filled with technicality and too scientific for such layperson. It is in fact subjective written and reads almost like a popular science book. Granted, some errors were discovered, but the authors have compiled and brought the data from the most important scientific works, including Clube's The Cosmic Serpent and The Cosmic Winter as well Catastrophes and Evolution: Astronomical Foundations to which I also recommend. In my opinion, it's a good book on the subject.

Meteoritics and impact phenomena are a fascination of mine and, with some anticipation, I purchased this book. I was disappointed. The treatment of impacts and their consequences was cursory for the most part and frequently conclusionary rather then illuminating. While the book contained a few facts not found in other, similar volumes, I felt book was written from hunger rather than love, if you will. The science and logic were frequently off the mark, in my view. Not the sort of book one would read for an in depth understanding of the topic.

Perhaps you have heard that a meteor strike may have killed the dinosaurs. Or, perhaps you have heard that a meteor struck the Earth in Siberia in 1908. But, did you know that another one struck Siberia in 1948, causing a cold war scramble on both sides of the globe? Or, that Colorado had a near miss just a few years ago? You would if you had read FIRE ON EARTH.

I discovered the Gribbins' book at the public library, but soon realized I would need my own copy (Thanks, Amazon!). It was perfect for me. I am writing a novel that is set a couple of decades after an asteroid strike. I needed a resource that would give me the the science of, and knowledge of, asteroid strikes on Earth. Yet, it had to be understandable by a non-scientist.

Here is a book that tells of the MANY impacts on the Earth over the past several million years, some even in our own lifetimes! These accounts are both fascinating and mysterious. And, as hard as it may be to imagine, they have found a way to inject humor into the telling.

The authors have the knack of presenting very complex scientific information and concepts in a way that almost anyone can understand. Not only that; they make it a fun read, too!

This is an excellent book on the topic of impacts and extinctions; the Gribbins especially deserve high praise for correcting one bit of scientific misinformation about terrestrial impact craters and ejecta. That is, that tektites--small, natural glassy objects are not formed on the Earth! It was long believed that tektites were the result of terrestrial impacts (an odd belief since the stone contain almost no water, but real impact glasses have lots of water, etc.). The Gribbens rightfully note that tektites are almost certainly extraterrestrial ejecta (and the Moon being a primary source). Ergo impact craters on Earth, where nickel/iron are not found and where pure glass material is found (i.e., Libyan Desert Glass, Darwin Glass, etc.), may really be the result of lunar glass meteorites impacting the Earth. That is, giant volcanic obsidian (silicic) domes ejected from the Moon during massive volcanic eruptions which crash to Earth! So, we don't have to look to the asteroid belt for mass extinctions--tektite showers may be the real culprits behind the extinctions! Kudos to the authors for penning a fascinating book which is clear, honest and not caught up entirely in today's impact mania catastrophism.