Two views of the Hiawatha crater region: one covered by the Greenland Ice Sheet, the other showing the topography of the rock beneath the ice sheet, including the crater. Image: NASA/Cindy Starr.

One of the largest impact craters on Earth has been discovered more than a half-mile under ice in northwest Greenland, NASA reported on Wednesday.

Why it matters: Per NASA, major impacts from asteroids like this have been proven in the past to "profoundly affect Earth's climate" and have serious consequences for life on the planet at the time of impact.

Details: The crater was first discovered in 2015 by researchers from the University of Copenhagen's Center for GeoGenetics at the Natural History Museum of Denmark, per NASA. They've been working since then to verify its origin. According to a news release, it measures around 1,000 feet deep and more than 19 miles in diameter, an area "slightly larger than that inside Washington's Capital Beltway."

How they did it: The researchers discovered the crater after inspecting a topography map of Greenland's ice sheet, NASA said. They "noticed an enormous, previously unexamined circular depression ... sitting at the very edge of the ice sheet."

  • The crater and the ice covering it were then mapped in May 2016 by a research plane studying Greenland ice melt.
  • In 2016 and 2017, researchers returned to the glacier in which the crater was found, the Hiawatha Glacier, to inspect sediments that had been washed out through a meltwater channel. One of the authors on the study, associate professor Nicolaj Larsen, from Aarhus University in Denmark, said in the release that some of the sediments they found had "planar deformation features indicative of a violent impact."

What's next: One of the researchers on the study — Joe MacGregor, a glaciologist at NASA Goddard Space Flight Center — told Axios that what "everyone would really like to know is how old the crater is." Finding that would requires a rock sample, which MacGregor said can be as small as a grain of sand, that scientists could date.

  • The age of the crater will indicate more clearly what its impact on Earth's climate was. For example, if there was ice there when it hit, MacGregor said, "that would have led to a lot of water being vaporized and melted, which would have made its way into the atmosphere and the ocean."

The bottom line: There's lots left on Earth yet to be discovered, MacGregor said.

"There are still large features of the landscape in our world waiting to be discovered, waiting to be found. That takes new measurements of different types, or it takes going to some remote places of the Earth ... but they're still out there. Just because we can map the world with satellite images relatively precisely, which is wonderful, that doesn't mean that we immediately understand all of that world."

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