One of the largest icebergs on the planet, about six times the size of Manhattan, has separated from an Antarctic glacier and is floating out towards open ocean. The iceberg is named B-31, and is roughly 255 square miles (660 square km). Its estimated maximum thickness is 1,600 feet (487 meters). Last Fall, it broke off from the Pine Island Glacier. Researchers have been watching it drift away since then, via satellite.
"The ice island, named B31, will likely be swept up soon in the swift currents of the Southern Ocean, though it will be hard to track visually for the next six months as Antarctica heads into winter darkness," according to scientists at NASA's Earth Observatory monitoring its progress.