Under its flat icy expanses, Antarctica is, like any other continent on Earth, wrinkled with mountains, ridges, and valleys. But only with radar can we penetrate through 40,000 years of accumulated ice and see the craggy landscape hidden below.

Winter is in full swing for us in the northern hemisphere, but summer is just getting underway in Antarctica. Summer is peak research season for polar scientists, who are currently drilling the deepest ice core ever at the South Pole. This ice core will reach down 1500 meters and through 40,000 years of ice; of course, this means you want to make sure you don't want to accidentally hit rock halfway down.

That's why NASA has recently released this radar cross-section of the South Pole, taken during an airborne surveying campaign all the way back in 1998. (Note: The horizontal and vertical scales are different to make it fit on a page.) This is still the most recent cross-section of the South Pole, and this year's ice core drillers consulted it for planning.

The image itself was taken from planes outfitted with radar equipment, whose microwave signals can penetrate through solid ground. Ice and rock return different echoes, making this under-ice view of the Antarctica possible. [NASA Earth Observatory h/t @coreyspowell]