Impact!: The Threat of Comets and Asteroids by Gerrit L. Verschuur (PDF)

Description

Most scientists now agree that some sixty-five million years ago, an immense comet slammed into the Yucatan, detonating a blast twenty million times more powerful than the largest hydrogen bomb, punching a hole ten miles deep in the earth. Trillions of tons of rock were vaporized and launched into the atmosphere. For a thousand miles in all directions, vegetation burst into flames. There were tremendous blast waves, searing winds, showers of molten matter from the sky, earthquakes, and a terrible darkness that cut out sunlight for a year, enveloping the planet in freezing cold. Thousands of species of plants and animals were obliterated, including the dinosaurs, some of which may have become extinct in a matter of hours. In Impact, Gerrit L. Verschuur offers an eye-opening look at such 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. The author recounts spectacular recent sightings, such as over Allende, Mexico, in 1969, when a fireball showered the region with four tons of fragments, and the twenty-six pound meteor that went through the trunk of a red Chevy Malibu in Peekskill, New York, in 1992 (the meteor was subsequently sold for $69,000 and the car itself fetched $10,000). 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). Indeed, we learn that in 1989, a bus-sized asteroid called Asclepius missed our planet by 650,000 kilometers (a mere six hours), and that in 1994 a sixty-foot object passed within 180,000 kilometers, half the distance to the moon. 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). He discusses Comet Swift-Tuttle–“the most dangerous object in the solar system”–a comet far larger than the one that killed off the dinosaurs, due to pass through earth’s orbit in the year 2126. And he recounts the collision of Comet Shoemaker-Levy 9 with Jupiter in 1994, as some twenty cometary fragments struck the giant planet over the course of several days, casting titanic plumes out into space (when Fragment G hit, it outshone the planet on the infrared band, and left a dark area at the impact site larger than the Great Red Spot). 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. Astronomer Herbert Howe observed in 1897: “While there are not definite data to reason from, it is believed that an encounter with the nucleus of one of the largest comets is not to be desired.” As Verschuur shows in Impact, we now have substantial data with which to support Howe’s tongue-in-cheek remark. Whether discussing monumental tsunamis or the innumerable comets in the Solar System, this book will enthrall anyone curious about outer space, remarkable natural phenomenon, or the future of the planet earth.

User’s Reviews

Reviews from Amazon users which were colected at the time this book was published on the website:

⭐I picked up this book on a whim, and found myself fascinated by the science. Its about the threat of comets and asteroids and the potential of collision with earth. If you are concerned, you should be, especially if the projectile is large and lands in the sea- deadly Tsunamis and tidal waves could be the result….look what happened to the dinosaurs! LOL, actually, the threat of being hit by a much smaller rock is far greater, Earth is hit every year by many small objects which most people never see or are noticed, (except by science-types).This book covers historical, ancient, and modern perspective towards the stellar apparitions. While parts are a little dry, it’s a good read for science geeks, or those interested in learning about asteroids and meteors. I found the author’s occasional witty commentary funny, and the historical notes fascinating. An excellent, read all-around. 4 stars.

⭐The chance of Earth being struck by a large asteroid or comet is neither more nor less now than it has ever been. If nothing else, this book will bring out that fact. So for all the folks who want to believe in the magical or the preposterous, such as Nostradamus, Velikovsky, and other fantasy spinners, go elsewhereIf, however, you are a person who accepts things scientific, this is your book. Professsor Verschuur is an excellent, lucid, organized writer who does not waste the reader’s time with forays into the specculative or ludicrous. Instead he forthrightly presents the overview of, and the detail behind, the genuine, if remote, danger that human society will receive heavy damage, if not outright destruction, from a large impact event. He accurately points out that the remoteness of this eventuality is offset by the magnitude of destruction that will occur if a large impact happens.I have studied impact phenomena for some years, and this book is the most-fact-filled, well organized book of its genre. It is not only an excellent starting volume for a study of this branch of science, but is a good wake-up call for organizing attempts to meet the danger. The Professor does not patronize his reader, but neither does he presume a level of knowledge beyond the ken of the average well-informed adult.I recommend the book very highly and would urge anyone interested in this topic to make it a priority purchase. It is the book by which all similar texts should be measured.

⭐Gerrit Verschuur has out together a well-researched if not particularly well-written book about asteroids and comets, and the danger that they present to life on Earth.He is not afraid to re-iterate himself; in fact one finds oneself reading the same thing re-phrased several times throughout the book and yet, he omits some things, for example names of sources of observations for brevity. I cannot help but think that an editor started work on the manuscript with some initial suggestions but the job was never completed. One error of paricular annoyance is his continued use of the word “loose” instead of “lose”. Was the editor on holiday when this was published?At the time of reading, the book is about twenty years old and therefore twenty years out of date. Despite this, we get lots of information on asteroids and comets and what they are likely to do when they collide with our planet. One obvious omission is the detailed discussion of potential methodolgies to divert these objects in their orbits away from a collision course. Perhaps there was reticence due to our poor understanding of the make up of these bodies.This book is ripe for a new edition with cleaned up text and an update on the science and knowledge that we have gained since, patchy as it still is.

⭐a good book but tsunami information now superceded by purdue/imperial research. still a very good laymans guide for those wanting advanced but not over technical information

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