NASA tweeted a photographed of a long, flat, rectangular iceberg last week, breaking up the popular (but false) notion that icebergs are always spiked mountains of frost rising formidably out of the ocean.
“The iceberg’s sharp angles and flat surface indicate that it probably recently calved from the ice shelf,” tweeted NASA ICE last Wednesday. Eventually, wind and water will wear down the edges.
The tabular iceberg, as it’s called, is believed to have broken off from the Larsen C ice shelf, which calved a berg the size of Delaware last year. Floating in the Weddell Sea off Antarctica, this iceberg is roughly a mile across, the BBC reports, with 90% of its mass hidden below the surface.
But why the aesthetically-pleasing right angles? Tabular icebergs are wide and flat due to the way they form: because they calve from floating ice shelves, there’s no friction with the ocean floor to hinder breakage, The Washington Post reports. Thus the ice breaks according to its crystalline structure—in a straight line.
NASA’s Operation IceBridge captured this image in one of its airborne surveys of the earth’s polar ice caps. The mission—which flies over Greenland from March to May, and over Antarctica in October and November—aims to better understand the connection between earth’s polar regions and the global climate.