81 Tut Jewel Formed By Asteroid Impact
The central jewel in King Tutankhamen's pectoral gear may have been literally out of this world—the result of an asteroid that exploded above the Sahara—according to Mark Boslough, a researcher at Sandia National Laboratories. In 1998 researchers elsewhere determined that Tut's jewel wasn't chalcedony but an unusual type of desert glass. Boslough, who was part of a team that created a computer simulation to predict what would happen when comet Shoemaker-Levy hit Jupiter, was later enlisted to figure out if the gem was meteoric in origin.
Boslough used Sandia's Red Storm supercomputer to ask what conditions would be required to melt Saharan sand into glass. The winning scenario: a 400-foot-wide stony asteroid that slammed into the air at 12 miles a second and exploded. For 20 seconds the resulting fireball would have been hot enough to melt quartz on the ground, creating glass that can still be found in the desert. Ancient Egyptians might have rightly recognized such ornaments as more precious than gold.
Michael Abrams
82 Secret Lakes Lie Under Polar Ice
A decade after Russian and British researchers announced the discovery of Lake Vostok, an enormous body of water more than two miles beneath the permanent ice sheet of Antarctica, two independent teams of scientists have evidence of other large subglacial lakes and rivers, and perhaps an entire watershed.
Robin Bell of Columbia University had long suspected that a slight depression on the surface of the ice indicated two additional, very large underground lakes, but this year she confirmed their existence with high-resolution measurements. The lakes, called 90°E and Sovetskaya, are each roughly the area of Lake Okeechobee in Florida; in Antarctica, only Lake Vostok is larger.
In April a group led by climate physicist Duncan Wingham of University College London announced the discovery of more subglacial lakes. They are linked by rivers that form when melting ice expands the lakes, increasing pressure under the ice cap and causing underground channels of water and mud to squirt out.
Instead of existing largely as separate entities, as experts had believed, the roughly 150 known lakes (and possibly thousands yet to be found) are likely part of a vast watershed, with streams periodically shooting from one lake to the next. While biologists long to sample this underground world for traces of life that may have been isolated for millions of years, the new evidence raises concerns that drilling for samples could contaminate the entire ecosystem.
Jeffrey Winters
90 Drillers Tap into Foundation of Earth's Crust
In April geologists reported that they had successfully drilled into the bottom layer of the ocean's crust for the first time—and so have come a step closer to understanding how the foundation of the world takes shape.
New crust forms at midocean ridges where the sea floor spreads apart. Lava leaking from the ridges creates the crust's upper layer; beneath that lies a second layer, composed of the fossilized channels that once piped molten rock to the ridges. The formation of the lowermost crust, made up of a dark, magnesium-rich rock called gabbro, is still largely a mystery, one that holds the key to the workings of the magma source that feeds the whole process.
Douglas Wilson, a geophysicist at the University of California at Santa Barbara, and his colleagues traveled 500 miles west of Costa Rica to an area of ocean floor that formed 15 million years ago. There they found just the right piece of crust—not too hot, not too thick, and not too crumbly—to drill down to the gabbro. In 2006 they released their findings: After drilling through nearly a mile of sediment and crust, they finally hit the gabbro layer for the first time. Wilson hopes to drill deeper into this third layer by 2009. Then he will truly plumb Earth's deep secrets.
Anne Sasso
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The scientific research drilling ship Joides Resolution is exploring the hidden |
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