With a gargantuan crack slowly splitting it apart, Antarctica’s fastest-melting glacier is about to lose a chunk of ice larger than all of New York City, scientists say.

The crevasse stretches 19 miles (30 kilometers) long and up to 260 feet (80 meters) wide, as shown in a picture taken by NASA’s Terra satellite in Octoberand featured this week as a NASA Image of the Day.

Snaking across the floating tongue of the Pine Island Glacier in West Antarctica, the crack is expected to create an iceberg 350 square miles (907 square kilometers)—versus 303 square miles (785 square kilometers) for Manhattan, Brooklyn, Queens, Staten Island, and the Bronx combined, according to NASA.

As for when the iceberg might shove off, “that is very difficult to predict,” said oceanographer Eric Rignot of NASA’s Jet Propulsion Laboratory, “but in the coming months for sure.”