July 16th, 2012 - the Petermann Glacier in northwest Greenland lost a massive iceberg, for the second time in three years. As the ice floating in the fjord broke up, the ice island was carried by the current down the glacier's outlet channel and toward the Nares Strait. Known as Petermann Ice Island 2012, it is bigger than Manhattan island - and floating at one kilometer per day. NASA's Aqua and Terra satellites made multiple passes each day over the polar regions, allowing scientists to track the ice island - whenever clouds didn't block the view. Scientists have been watching this crack develop since 2001. Ocean temperatures are one factor determining when glaciers will calve an iceberg. Warmer water destabilizes the ice. After two months at sea, Petermann Ice Island 2012 had begun to fragment as it floated down the strait.