NASA announced on Thursday that a massive canyon that has been unknown for all of human history has been found under a mile of ice in Greenland.

An airborne research project known as Operation IceBridge discovered the canyon via ice-penetrating radar signals. Under the multimillion-year-old sheet of ice lies a landscape that has never been seen by human eyes.

Analyzing data collected from between 2009 and 2012, scientists have concluded that the canyon is 460 miles long, extending from northern to central Greenland, making it longer than the Grand Canyon. At its deepest points, the canyon is more than 2,600 feet deep.

"One might assume that the landscape of the Earth has been fully explored and mapped," said Jonathan Bamber, Bristol University professor of physical geography and lead author of the canyon report. "Our research shows there's still a lot left to discover."

Watch video about this story, embedded below via NASA:

[hat-tip to TPM]