Rocks

from

Space!!

 

[July 2003] There was a time a few centuries ago when the idea that rocks could fall from the sky was considered crazy. Even when the idea of meteors as pieces of rock entering the atmosphere became commonplace in the late 1800's, it was still not considered possible that some of these rocks could be big enough to leave behind craters or 'astroblems' on Earth's surface. The late geologist Eugene Shoemaker was the first scientist to prove conclusively in 1963 that the famous Arizona 'Barringer' Crater was actually a meteor impact crater caused by the explosion following an impact, and not a caldera or volcanic steam vent. The first time an impact theory had been proposed was by 1891, but even bythe 1950's there were still many scientists who doubted this proposal, even to explain the craters on the moon.

Friedrich Chladni is usually called the Father of Meteoritics. In 1794 he published a book that declaired that, not only were meteors associated with stones that fell from the sky, but that they originally came from space. His idea was ridiculed by many as being completely preposterous. Up until then, there had been many eyewitnesses to actual meteor falls and some historic recoveries of stony or iron material, but these were usually considered unreliable anecdotes by the learned community.

The tide turned in 1803 when the town of L'Aigle in Normandy France was bombarded by thousands of fragments which were then analyzed by the famous physicist Jean-Baptiste Biot who declared them to be rocks from space.

After a December 1807 spectacular fireball and meteorite recovery in Weston, Connecticut, Thomas Jefferson, President of the United States, responded with great skepticism: "Gentlemen, I would rather believe that two Yankee professors would lie than believe that stones fall from heaven."

Today we have a bewildering amount of information that confirms these ideas, and also places them in a context of how planets form, and how the very course of evolution can be altered as certain impacts cause mass extinctions. The literature on the web is extensive on any one of these issues, so instead I want to note some of the more interesting episodes, some recent and some ancient.

Here is an Interactive Map of terrestrial impact craters. It shows that Earth has been a sitting duck for billions of years, and that erosion has not been able to completely erase traces of many of the more spectacular impacts in the last billion years. The most recent major impact is the Dinosaur Killer about 65 million years ago, whose crater was found off the coast of Honduras buried under sedimentary deposits.

Infrasound sensors set up by the Military are regularly detecting the detonations of meteors in the atmosphere that are 10-50 feet across and explode with the force of a small nuclear weapon. Several of the larger ones would rival the Hiroshima Bomb in their energy. Many of these atmospheric detonations probably coincide with strange explosions and 'brondids' that have been heard for hundreds of years.

On October 9, 1992 the Peekskill Meteorite damaged Michelle Knapp's car, which has now become world-famous. Meteorites have a long history of causing damage to property, and not only injuring people but killing them. Chinese records indicate that dozens of people have been killed over the last thousand years or so in China. Even the Old Testament has a dramatic story of stones falling from the sky and killing an army!

On March 28, 2003 a rain of meteorite fragments in Kansas caused a lot of property damage but no injuries.

I'll add more to this page in the near future!!!