Nasa discovers mile-wide, perfectly rectangular iceberg

The extraordinary 'monolith' has edges so clean they look as if they've been cut with a knife

Nasa has spotted a huge, mile-wide iceberg with edges so smooth they look like they have been cut with a knife.

The "monolith" was seen floating in the Antarctic among sea ice and seems to have broken off the Larsen C ice shelf.

The clean and clear cut of the edge of the ice shows that the iceberg is relatively freshly broken off from the shelf, said the Nasa scientists who spotted it from a plane.

Images taken during that trip show what is known as a "tabular iceberg". Unlike the iconic shape that might be full of crags and breaks, such objects are distinguished by their long flat tops and clean-cut edges – and can extend hundreds of miles wide, as well as reaching deep beneath the surface.

The tabular icebergs form when their weight snaps them off from the ice shelves they were once part of, often breaking off with the kind of clean precision as seen in the new image. They can then drift off on their own, and might smash apart once they do into the more rough-looking icebergs that are famous for sinking the titanic.

Though a mile-wide might sound like a lot, icebergs formed by calving events such as this can actually be far more vast, and this might even be a relatively small specimen. Last summer, a different iceberg known as A-68 detached from the same Larsen C ice shelf – and that had a surface area of over 2,000 miles, with much of its giant size being underwater.