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Earth Impacts III

January 8, 2014

More than 3,000 years ago, Egyptian jewelers fashioned a magnificent brooch for the pharaoh Tutankhamen. Its centerpiece was a scarab beetle made of golden glass — a representation of the Sun god, Re. The glass itself was formed when a fireball brighter than the Sun blazed through the skies of the ancient Sahara.

A recent study says the fireball was a comet that slammed into Earth’s atmosphere more than 28 million years ago. Pressure caused it to explode. The intense heat melted some of the desert sands, forming glass.

Earth has been hit by many asteroids and comets. Traces of only a few of them remain — in the form of bowl-shaped impact craters, layers of shattered rock, or blobs or droplets of glass.

Geologists have long known that the Saharan glass formed as the result of some type of cosmic collision. The recent study, by researchers in South Africa, says the colliding object was an icy comet. In fact, the researchers say this is the best evidence yet of a comet hitting Earth.

They analyzed a small rock found in the same area as the desert glass. It contains microscopic diamonds that likely formed quickly under intense pressure. The chemistry of the rock suggests an extraterrestrial origin — most likely a comet.

Regardless of whether the object was a comet or an asteroid, it’s likely that a fireball seared the desert sands — providing the raw material for a decoration fit for a king.

More about cosmic collisions tomorrow.


Script by Damond Benningfield, Copyright 2013

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