Synopsis
Ensconced in our tiny solar system and warmed by the Sun, the Earth seems safely removed from the vast dangers and unpredictability of outer space. However, in Fire on Earth, authors John and Mary Gribbin explain that every so often, comets and asteroids from the depths of space collide with the Earth, wreaking havoc on its inhabitants and altering the course of history.
Satellite photographs of the Earth taken from space show that the surface of our planet is pockmarked, evidence of numerous cosmic impacts that have occurred for millions of years. In 1990, one such crater was discovered in Mexico's Yucatan peninsula, and was determined by scientists to have been caused by a huge asteroidal collision that led to the extinction of the dinosaurs.
More recently, astronomers have discovered a giant comet beyond the orbit of Jupiter that is hurtling towards the Sun and that will provide a spectacular astral display as it shoots across the sky in 1997. Although it will not strike the Earth, it is similar in size and structure to the comet that did collide with our planet sixty-five million years ago, ushering in a devastating ice age that caused dramatic environmental changes the world over.
In Fire on Earth, renowned science writers John and Mary Gribbin argue that such events have been instrumental in shaping the course of natural - and thus human - history.
Tracing the history of these unpredictable and violent collisions, from prehistory to the present, the authors paint a sobering picture of the many dangers our fragile planet faces, and discuss the disastrous environmental consequences that may ensue. Explaining that these impacts and close encounters occur far more frequently than we believe, the Gribbins address the unsettling but vital question of what we can do when an Earth-bound comet is discovered.
Reviews
A crater discovered in Mexico's Yucatan Peninsula in 1978, and intensively investigated in 1990, may provide the "smoking gun" confirming that the extinction of the dinosaurs was caused by a meteorite that smashed into Earth 65 million years ago, wiping out 70% of all plant and animal species. The Gribbins, popular science writers, consider the evidence for this theory overwhelming. Collisions with comets, scientists now believe, have resulted in mass extinctions on Earth every 26 to 30 million years. Lesser cosmic impacts, the Gribbins hypothesize, shaped the evolution of human civilization by triggering ice ages. The Tunguska explosion of 1908, which produced a devastating fireball in Siberia that destroyed forests and caused worldwide tremors, was the result of an asteroid or meteor, they believe. More speculative is their proposal that a cataclysmic collision triggered the collapse of Roman Britain around A.D 500. Fragments of the Shoemaker-Levy comet rammed into Jupiter in 1994. To monitor the possibility of similar catastrophes on our planet, the Gribbins strongly endorse NASA's proposed Spaceguard Survey, a scheme to identify threatening asteroids and comets using a network of as-yet-unbuilt telescopes. Free of sensationalism, this is popular science writing at its most lucid and entertaining.
Copyright 1996 Reed Business Information, Inc.
Here is an able summary of the growing body of evidence that Earth has sustained a number of collisions with various large objects from space. John Gribbin (In the Beginning, 1993, etc.) and his wife are a versatile British team of popular-science writers, and the story of asteroid collisions calls on their wide range of scientific knowledge. The discovery of high concentrations of the element iridium (rare on Earth, but common in meteors) in the geological strata marking the end of the Cretaceous Period led a team of chemists and geologists to the conclusion that a large meteor impact had occurred at that time, probably causing the death of the dinosaurs. This theory initially met with widespread skepticism, but the evidence for it has continued to accumulate. The authors summarize the Tunguska event, a probable meteor impact in Siberia in 1908, and another that took place in the same region in 1947. There have been a few spectacular near- misses--one fireball seen over Montana in 1972, another over the Pacific in 1994. Impact craters on the moon and other planets testify that over geological time spans these events are far from rare. And the collision of Comet Shoemaker-Levy with Jupiter made it abundantly clear how powerful such a collision would be. The volume of space around the Earth as well as beyond our solar system contains a large number of comets, meteors, and small asteroids. Large objects, the size of the dinosaur killer, seem to arrive with a periodicity on the order of 30 million years. The Gribbins also discuss the possibility of a periodic swarm of smaller objects every few thousand years, causing widespread damage and disrupting civilization. Finally, they discuss various plans being made to detect and possibly deflect an incoming object--concluding that such efforts are unlikely to be of value in the foreseeable future. A well-written and comprehensive discussion of a sobering but inevitably fascinating subject. -- Copyright ©1996, Kirkus Associates, LP. All rights reserved.
Most science readers are familiar with the widely accepted theory that the impact of an object from space led to the extinction of the dinosaurs. Accumulating evidence suggests that this was no isolated incident but that numerous bombardments and massive extinctions have occurred regularly, with consequent shifts in the patterns of evolution and major climatic changes such as the Ice Ages. Presenting the history, discovery, and theories about such devastating impacts, best-selling science writers John and Mary Gribbin (Schroedinger's Kittens and the Search for Reality, LJ 5/1/95) present an enthralling story of how astronomical events have determined biological development on Earth. Their work is recommended as an excellent introduction to catastrophic collisions, but it will also satisfy library patrons who've already read Duncan Steel's Rogue Asteroids and Doomsday Comets (LJ 51/95) or John Lewis's Rain of Fire and Ice (LJ 1/96) and who are begging for more on this exciting and controversial topic.?Valerie Vaughan, Hatfield P. L., Mass.
Copyright 1996 Reed Business Information, Inc.
Able and prolific science popularizers, the Gribbins turn their attention to that worldwide attention-getter of 1993: the Jupiter-comet collision. Wondering if it can happen to Earth, the Gribbins retell the discovery of the principal terrestrial evidence that it already has--the iridium layer and crater in Mexico confirming a cataclysmic, dinosaur-extinguishing collision. Where in the solar system such cosmic killers come from next occupies their presentation as they provide statistics for known Earth-crossing asteroids and comets. The source of the comets is the long-theorized and recently proven Kuiper Belt. Located just beyond Neptune, it harbors three dozen known and 35,000 probable comets, all susceptible to being drawn toward new orbits in the inner solar system. Speculating about the frequency of collisions with Earth by rogue comets, the Gribbins cite the numbers calculated by astronomers, which are uncomfortable enough (1 chance in 10,000 per century) to warrant keeping the telescopes on alert. Concluding this early warning by describing the technologies that could avert a disaster, the Gribbins have usefully unified information that is otherwise scattered in such periodicals as Scientific American. Gilbert Taylor
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