We might not know a whole lot about what’s going on inside Mars, the Moon, or even the deepest reaches of Earth’s oceans, but scientists have a pretty clear picture of the Earth’s surface. Or at least they thought they did. A new discovery in Greenland could help to rewrite some recent Earth history, and it’s all thanks to ice.

Using new, more powerful radar technology to examine what’s hiding beneath Greenland’s massive ice sheet, a team of researchers from around the world just made an incredible discovery. There, hidden under the ice, is a massive impact crater that was just waiting to be found.

The team, which was led by scientists from Denmark’s Natural History Museum, as well as the University of Copenhagen, was curious about a strange circular feature on the edge of Greenland’s ice sheet. It looked far too perfect to be a coincidence, based on data gathered by NASA’s Operation IceBridge, which had done flyovers to map the area.

To get an even better glimpse at what might be hiding there, new flyovers with a powerful ice-penetrating radar setup were performed, and the resulting map of the ground beneath the ice proved what the team had suspected: there’s a crater there, and it’s quite large.

“Previous radar measurements of Hiawatha Glacier were part of a long-term NASA effort to map Greenland’s changing ice cover,” Joe MacGregor, a glaciologist with NASA, explains. “What we really needed to test our hypothesis was a dense and focused radar survey there. The survey exceeded all expectations and imaged the depression in stunning detail: a distinctly circular rim, central uplift, disturbed and undisturbed ice layering, and basal debris — it’s all there.”

Subsequent studies of the area, in which samples were gathered from rocks and streams flowing down from the glacier, supported this discovery and showed that the area had received a massive impact not that long ago. The strike is thought to have happened less than three million years ago, and the meteorite was over half a mile wide, according to the researchers.