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More than a decade ago a large iceberg (over a thousand square miles in area, and a quarter of a mile thick) broke off an Antarctic glacier and drifted into the Southern Ocean. The National Iceberg Center, which monitors sea ice in shipping lanes, christened the giant B10 in 1992. In 1995 B10 split into two pieces. Amazingly, the larger piece (B10A) was still the size of Rhode Island. By the summer of 1999 it had moved out of the isolated waters around
Antarctica and near the Drake Passage, which ships use to navigate around the southern
tip of South America.
This true color Landsat 7 image shows relatively small icebergs "calving" off the edge of B10A. Since B10A is now in relatively warm water, it is breaking up more rapidly than before. The new icebergs are drifting into
international shipping lanes, posing a threat. Remote sensing satellites such as Landsat 7, SeaWinds, and Radarsat are being used to monitor B10A and its child icebergs.
The mega-iceberg A53a (upper image) measured close to 50 kilometers by 22 kilometers, about seven times the area of Manhattan Island, in mid-January 2008 when astronauts took the photographs for this mosaic. The images were acquired from the International Space Station (ISS), located 780 kilometers to the north of the iceberg at an altitude of 341 kilometers; the perspective distorts the oblong shape of the iceberg, making it look squarer than it actually is.