NASA scientists have discovered an unusual rectangular iceberg floating off the Larsen C ice shelf in Antarctica.

Key points: NASA's IceBridge flight was conducting airborne survey of Arctic and Antarctic ice

NASA's IceBridge flight was conducting airborne survey of Arctic and Antarctic ice Sharp angles and flat surface of iceberg indicate it probably recently broke off the ice shelf

Sharp angles and flat surface of iceberg indicate it probably recently broke off the ice shelf Rectangular iceberg appears to be freshly calved from Larsen C which released the massive A68 iceberg in 2017

Images of the unusual icebergs were captured on NASA's IceBridge flight, an airborne survey of Arctic and Antarctic ice yielding detailed, three-dimensional views of ice sheets, ice shelves and sea ice.

According to scientists, the iceberg's sharp angles and flat surface are an indication that it had probably recently broken off the ice shelf.

"I often see icebergs with relatively straight edges, but I've not really seen one before with two corners at such right angles like this one," Operation IceBridge senior support scientist Jeremy Harbeck said.

Scientists were more interested in iceberg A68 (in the distance) but thought the straight-edged iceberg was more photogenic. ( NASA: Jeremy Harbeck )

In a different photo, Mr Harbeck captured both the edge of the now-famous iceberg, and a slightly less rectangular iceberg.

"I was actually more interested in capturing the A68 iceberg that we were about to fly over, but I thought this rectangular iceberg was visually interesting and fairly photogenic, so on a lark, I just took a couple of photos," Mr Harbeck said.

The iceberg's sharp edges and flat surface suggest it only recently broke off the ice shelf. ( NASA: Jeremy Harbeck )

The rectangular iceberg appeared to be freshly calved from Larsen C, which in July 2017 released the massive A68 iceberg, a chunk of ice about 5,000 square kilometres.

The flight originated from Punta Arenas, Chile.

Flights are conducted over Greenland from March to May and over Antarctica in October to November.

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