Researchers believe that a 1-kilometer-wide iron meteorite caused the 31-kilometer-wide impact crater, perhaps as little as 12,000 years ago. It's the first such crater found under any of Earth's ice sheets.
Image: Natural History Museum of Denmark, Cryospheric Sciences Lab, NASA Goddard Space Flight Center, Greenbelt, MD, USA
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The vast hole discovered beneath the ice of the the Hiawatha Glacier in northern Greenland is believed to be among the 25 largest impact craters on Earth, according to a study published in the journal Science Advances.
Initially discovered in 2015, an international team of researchers has been working on verifying the findings since then, with much more still to do.
Professor Kurt H Kjaer of the Centre for GeoGenetics at the Natural History Museum of Denmark said that the crater was not dated but "its condition strongly suggests that it formed after ice began to cover Greenland, so younger than 3 million years old and possibly as recently as 12,000 years ago — toward the end of the last Ice Age."
Sediment samples from the site of the crater confirmed that an iron meteorite, thought to have been around a kilometer (0.6 miles) wide, caused the 31-kilometer (19-mile) impact crater.
"The crater is exceptionally well-preserved, and that is surprising, because glacier ice is an incredibly efficient erosive agent that would have quickly removed traces of the impact," Kjaer said.
The site of the crater in Inglefield Land, GreenlandImage: Natural History Museum of Denmark
The impact would have had far-reaching effects on the planet, according to the researchers.
"There would have been debris projected into the atmosphere that would affect the climate and the potential for melting a lot of ice, so there could have been a sudden freshwater influx into the Nares Strait between Canada and Greenland that would have affected the ocean flow in that whole region," said co-author John Paden of Kansas University.
Summer is shooting star season
In mid-August, showers of meteors hit Earth. The Perseids return at the same time every year. Open your eyes, you may see a wish come true!
Image: Imago/Leemage
You could almost set your clock to them
Every summer, a large number of shooting stars burn up in our atmosphere. Their names derive from the constellations in our night sky where they appear. In August most of the Perseids will come down, named after the constellation of Perseus. July was already the high point of the Aquariids, named after Aquarius.
Image: picture-alliance/dpa/P. Pleul
That's how they come about
The dates for the shooting star showers are the same every year, because they're in line with the solar calendar. Every year on the same day, Earth passes through trails of dust left behind by comets.
Image: Pond5 Images/IMAGO
Tiny particles - shining bright
This is what happens when tiny dust particles enter our atmosphere and burn up. These meteors only have a diameter of one millimeter to one centimeter. The bigger they are, the more beautiful the shooting star appears in the sky.
Image: picture-alliance/dpa/D. Reinhardt
Not just in the summer
There are also times in the winter when Earth passes through trails of comet dust. Then the chances of seeing a shooting star are good, as well — for example in November and December. That's when the Leonids and the Geminids hit our planet.
Image: Pedro Punte Hoyos/EFE/imago images
Getting away from the city lights
The best place to observe the shooting stars is far away from artificial light sources, somewhere in nature on a warm summer evening, perhaps, provided there is not constant rain.
Image: picture-alliance/dpa/V. Lannert
For tougher nature lovers
Those not afraid of putting on warm winter clothing and going out at night have another option: Enjoy the shooting stars on a cold winter night on top of a mountain. Clear skies and high pressure weather systems make for optimal conditions.
Image: Imago/Eibner
Don't forget your wishes
Even if you're watching shooting stars purely for scientific interest, don't forget to wish someone something good, when you see a meteor. Important: Don't tell anybody, though, otherwise your good intentions will not come true.
Image: picture-alliance/dpa
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The research team used ice radar to map the tectonic structures of the rock, after NASA's Program for Arctic Regional Climate Assessment and Operation IceBridge first located the site.
Researchers plan to try to recover material that melted after the impact from the bottom of the glacier, hoping to learn precisely when the meteorite fell and how it affected the area.
