IMPACT! by Gerrit L. Verschuur


The Threat of Comets and Asteroids
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 Verschuur, an astronomer (Hidden Attraction, 1993), offers a detailed and alarming account of the meteors and comets that have struck the Earth in the past, with devastating consequences, and reminds us that such disasters are likely to reoccur. He begins his account in 1980 with the discovery of an anomalous concentration of the element iridium at the geological boundary between the Cretaceous and Tertiary eras--the point at which the dinosaurs became extinct. Rare on Earth, iridium is far more common in comets and meteors; this discovery led to the theory that a massive comet striking the earth with the impact of 20 million hydrogen bombs led to the death of the dinosaurs. At first reluctant to accept the concept, many geologists were eventually brought around by the discovery of a massive impact crater near Yucat†n. Verschuur then examines both the geological and astronomical evidence for frequent large impacts: the presence of other craters on Earth (145 had been identified by 1995), the prevalence of craters on other bodies of the solar system, the large number of astronomical bodies in near-Earth orbits, historical accounts of comet or meteor impacts. Verschuur places great emphasis on the possibility of a large, devastating strike in the near future. He also gives particular attention to the consequences of an ocean impact (in fact, the most likely scenario), with huge tsunamis crashing hundreds of miles inland. And he considers courses of action we might take, emphasizing a program to detect (and possibly deflect) the menaces from space. Verschuur argues that we should seriously entertain the prospect of moving some of Earth's population off the planet, to allow the human race to survive an unpreventable large strike. Occasionally overblown, often jumpy in its organization, this is nonetheless a strong treatment of one of the key scientific discoveries of our time. (40 halftones, 3 linecuts, not seen)

Pub Date: Sept. 1st, 1996
ISBN: 0-19-510105-7
Page count: 224pp
Publisher: Oxford Univ.
Review Posted Online:
Kirkus Reviews Issue: July 15th, 1996