We may have our eye turned towards exploring space, but apparently, there's still very much here on Earth we have yet to see. After collecting data for years, scientists have just announced the discovery of a 460-mile-long canyon underneath Greenland's ice sheet, making it even longer than our own Grand Canyon—and no human has ever laid eyes on it before.

Hidden by a thick layer of ice for the entirety of humanity, the half-mile-deep canyon was uncovered thanks to an ice-penetrating radar, which revealed something mimicking the shape of a winding river. According to Jonathan Bamber, a professor of physical geography at the University of Bristol in the United Kingdom and lead author on the study:

One might assume that the landscape of the Earth has been fully explored and mapped. Our research shows there's still a lot left to discover.

It's only just now that we're discovering this massive geological structure thanks (partially) to thousands of miles of airborne radar data that NASA has been collecting from the United Kingdom and Germany for several decades. The rest of the data came from NASA's airborne science campaign Operation IceBridge's own data acquired between 2009 and 2012. Specifically, something called the Multichannel Coherent Radar Depth Sounder—one of the IceBridge's instruments and the pièce de résistance that made this whole discovery possible—was what allowed the researchers to see through incredibly thick layers of ice to the bedrock below.

When they tuned their radars to just the right frequency, the scientists were able to send out radio waves that would travel through the ice, bounce off the bedrock underneath, and come all the way back up. Meaning the longer a radiowave takes to come barreling back, the deeper that particular bit of canyon is.

And though we're almost positive that the canyon predates humanity, scientists have reason to believe that it came before Greenland's massive, overlying ice sheet, as well. In fact, evidence seems to suggest that about 4 million years ago, water flowed into the canyon from Greenland's interior and back out into the Atlantic ocean.

The IceBridge campaign won't head back to Iceland's chilly shores again until March 2014, but when it does, it's clear that there's still very much to look forward to. [NASA]