Published: Чт, Ноября 15, 2018
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Scientists confirm massive impact crater beneath Greenland’s ice

Scientists confirm massive impact crater beneath Greenland’s ice

A 31-kilometre-wide crater under a Greenland ice sheet indicates a kilometre-wide meteorite smashed into the Earth sometime between 12,000 and 3 million years ago, and could have had a "profound" impact on the climate.

The crater is buried more than half a mile under ice in Greenland, according to NASA. "We suspect these initially detached in Earth's gravity field and then decelerated as they entered the atmosphere to fall south of the Hiawatha crater".

The crater was first discovered in July 2015 as the researchers inspected a new map of the topography beneath Greenland's ice-sheet.

Co-author John Paden, a professor of electrical engineering and computer science at the University of Kansas, said: "We've collected lots of radar-sounding data over the last couple of decades, and glaciologists put these radar-sounding data sets together to produce maps of what Greenland is like underneath the ice".

"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", Professor Kurt H Kjær said.

"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".

Is there proof of an asteroid impact?

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In the summers of 2016 and 2017, the research team returned to the Hiawatha Glacier to map tectonic structures in the rock near the foot of the glacier and collect samples of sediments washed out from the depression through a meltwater channel.

This helped the experts make an important discovery.

A number of iron meteorites, including a 20-tonne fragment kept at the Geological Museum in Copenhagen, had previously been found in the area around Cape York, not far from Hiawatha, leading scientists to believe an impact must have occurred in the region, a theory which lacked evidence until now.

The analysis revealed metals among the material, heavily suggesting the "presence of a meteorite".

Sadly, although there's evidence of a huge impact, it's still not clear how life on Earth would've been impacted.

Accurately dating the collision will provide future research with a better understanding of the consequences of such an impact and how it affected the environment on the Earth.

Some, including Kring, believe that the impact crater is not an asteroid, but Nicolaj Larsen is confident that it came from space, even if the impact to the planet's climate or life may not yet be known.

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