Pieces of a giant asteroid or comet that broke apart over Earth may have crashed off Australia about 1,500 years ago, says a scientist who has found evidence of the possible impact craters. Satellite measurements of the Gulf of Carpentaria (see map) revealed tiny changes in sea level that are signs of impact craters on the seabed below, according to new research by marine geophysicist Dallas Abbott. Based on the sat

ellite data, one crater should be about 11 miles (18 kilometers) wide, while the other should be 7.4 miles (12 kilometers) wide. For years Abbott, of Columbia University's Lamont-Doherty Earth Observatory, has argued that V-shaped sand dunes along the gulf coast are evidence of a tsunami triggered by an impact. "These dunes are like arrows that point toward their source," Abbott said. In this case, the dunes converge on a single point in the gulf—the same spot where Abbott found the two sea-surface depressions. read more in>>>>

"If Pandora existed, we potentially could detect it and study its atmosphere in the next decade," said Kaltenegger of the Harvard-Smithsonian Center for Astrophysics (CfA). So far, planet searches have spotted hundreds of Jupiter-sized objects in a range of orbits. Gas giants, while easier to detect, could not serve as homes for life as we know it. However, scientists have speculated whether a rocky moon orbiting a gas giant could be life-friendly, if that planet orbited within the star's habitable zone (the region warm enough for liquid water to exist). read more in>>>>