When Worlds Collide
from the book, "Our Fascinating Earth"

Book: 
Our Fascinating Earth

When Worlds Collide

On August 10, 1972, our planet narrowly escaped collision with a meteor. On that day a blazing white ball resembling a giant welder's torch, trailing a long tail of smoke in its wake, soared over the western United States and Canada. It was a thirteen—foot object weighing at least 1,000 tons and flew at more than nine miles per second!

It was first spotted over Utah. A minute and a half later it was seen over Alberta, Canada. Had it collided with the earth, its punch would have been equal to that of the atom bomb exploded over Hiroshima during World War II. However, instead of hitting the earth, it virtually ricocheted off the atmosphere and flew harmlessly back into space. It seems rather startling that, after finding its way here across billions of miles of space, the meteor missed hitting the earth by a mere thirty—five miles!

News of this near miss was considered so frightening that details of it were kept secret from the public for the next two years.

The collision of large meteors with the earth could be devastating. Such an event occurred millions of years ago in the Shetland Islands, creating St. Magnus Bay. The bay is ten miles across and 540 feet deep at the center. Admiralty charts show the ridge around it forms an almost perfect circle. Scientists believe that the bay was excavated by the impact of a two—million—ton meteorite over 1,000 feet in diameter. It struck the Shetland Islands over a million years ago at a velocity of twenty—five miles per second — the ground must have indeed shaken.

More recently a large meteorite did collide with the earth, and it very nearly caused the destruction of Pittsburgh. On the evening of June 24, 1938, Pittsburgh, Pennsylvania, was rocked by a terrific explosion. Many people, seeing a brilliant flash across the sky and hearing the noise, naturally thought a powder magazine had exploded. The light and explosion were actually caused by the impact of an unusually large meteorite that struck beyond the western city limits. Had it fallen at a slightly different angle, it would have destroyed much of the city and killed at least half a million people!

However, this disaster would have been small indeed compared with a more recent near confrontation with an object from outer space. This close encounter occurred in March 1989, during the recent memory of practically every reader. Scientists detected the approach of a moderately large asteroid. It was well over half a mile in diameter and weighted many millions of tons. It did not come nearly as close as those listed so far, but it did pass within 500,000 miles of earth. As an encounter with a celestial body, this is considered very close, and scientists refer to it as a cosmic near miss.

The destruction that would result were an object of this size to collide with the earth is unthinkable. If it had, for instance, hit the same spot as the Pittsburgh meteorite, the city of Pittsburgh would now be nothing but a gigantic hole in the ground!