Impact!: The Threat of Comets and Asteroids

Gerrit L. Verschuur0195101057, 9781423739043, 9780195119190, 9780195101058, 0195119193

In Impact, Gerrit L. Verschuur offers an eye-opening look at catastrophic collisions with our planet. Perhaps more important, he paints an unsettling portrait of the possibility of new collisions with earth, exploring potential threats to our planet and describing what scientists are doing right now to prepare for this awful possibility. Every day something from space hits our planet, Verschuur reveals. In fact, about 10,000 tons of space debris fall to earth every year, mostly in meteoric form. But meteors are not the greatest threat to life on earth, the author points out. The major threats are asteroids and comets. The reader discovers that astronomers have located some 350 NEAs (“Near Earth Asteroids”), objects whose orbits cross the orbit of the earth, the largest of which are 1627 Ivar (6 kilometers wide) and 1580 Betula (8 kilometers). Comets, of course, are even more deadly. Verschuur provides a gripping description of the small comet that exploded in the atmosphere above the Tunguska River valley in Siberia, in 1908, in a blinding flash visible for several thousand miles (every tree within sixty miles of ground zero was flattened). In addition, the author describes the efforts of Spacewatch and other groups to locate NEAs, and evaluates the idea that comet and asteroid impacts have been an underrated factor in the evolution of life on earth.

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Table of contents :
Contents……Page 12
1 The Killer Strikes……Page 16
2 The Saga of the Chicxulub Crater……Page 30
3 Solar System Debris……Page 45
4 Something about Comets……Page 63
5 The Birth of the Earth……Page 77
6 The Nineteenth-Century Perspective……Page 88
7 Twentieth-Century Rumblings……Page 100
8 Comet Impacts in History……Page 108
9 On the Edge of Extinction……Page 121
10 Reconstructing the Crime……Page 133
11 Death Star or Coherent Catastrophism?……Page 141
12 Craters and Tsunamis……Page 153
13 Offering Odds on Impact……Page 169
14 The Great Comet Crash of 1994……Page 182
15 The Aftermath……Page 195
16 The Search……Page 204
17 Dodging the Asteroids?……Page 217
18 Our Place in Space……Page 225
Bibliography……Page 236
G……Page 240
R……Page 241
Z……Page 242
A……Page 244
C……Page 245
G……Page 246
M……Page 247
O……Page 248
T……Page 249
Z……Page 250