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In a remote area of Northwest Greenland,
an international team of scientists have made a stunning discovery
buried beneath a kilometer of ice. It's an impact crater
300 meters deep, 31 kilometers wide
much bigger than Washington D.C.,
even bigger than Paris,
and it's probably one of the youngest large impact craters on Earth.
In May 2016, the team sent the German research plane Polar 6
to fly over Hiawatha glacier with a powerful new ice-penetrating radar.
Radar waves can travel through ice measuring its thickness and internal structure.
Studying data from this airborne survey,
the scientists confirmed the tell-tale bowl shape
and central peaks beneath Hiawatha Glacier.
They also found that the oldest ice in the crater was actually fairly young, by Greenland standards,
and had experienced a great disturbance in its flow
towards the end of the last ice age.
The Hiawatha crater is one of the 25 largest known impact craters on Earth,
and the first found under any of our planet's ice sheets.
The data as a whole suggests it's quite young, geologically speaking.
An impact of this size is unlikely to happen again soon,
but evidence that it might have happened not so long ago in Earth's history
is essential to assessing the risk today.
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