A massive asteroid crater has been discovered under a continental ice sheet in Greenland. With its sheer size, the crater is now considered to be one of the 25 biggest impact craters to be found so far on Earth.
The crater measures roughly 31 kilometers (19 miles) in size — which is the equivalent of it being the size of France’s capital city, Paris, according to the Independent. It is estimated that the asteroid hit the Earth sometime between 3 million and 12,000 years ago, Gizmodo added.
The crater was detected beneath the Hiawatha Glacier in northwest Greenland. A group of researchers from the Centre for GeoGenetics at the Natural History Museum of Denmark and University of Copenhagen have been investigating the crater and have recently published their findings in Science Advances.
The iron-rich asteroid, while creating a massive crater, is believed to have been just under one kilometer (0.62 miles) wide when it struck the Earth. Such an impact would have likely led to global cooling, thanks to water vapor and debris being flung into the air after impact. But how did such a massive crater remain hidden for so long?
While the initial impact would have created a massive wound in the earth, over time, the glacier has helped to conceal its existence. The Hiawatha glacier is over 1,000 meters tall, according to Gizmodo, so such a vast sheet of ice would easily obscure the crater from sight.
1st impact crater found under ice sheet! Meteorite slammed into Greenland probably after ice sheet began forming 3 million yrs ago. Radar identifies 31km wide depression in bedrock, beneath 1km of ice. Est. size of space rock? 1.5km-wide, 10 billion tonnes https://t.co/wyw5Dmwsfi pic.twitter.com/Sv7viFZbrR— The Antarctic Report (@AntarcticReport) November 15, 2018
And, as a result of this, the crater was actually discovered by chance in July of 2015.
Nicolaj K. Larsen, a co-author of the study and a geoscientist at Aarhus University, revealed how the crater was found.
“In 2015 I was looking at a new map of the bedrock below the Greenland Ice Sheet and discovered a large circular feature under the Hiawatha glacier in northwest Greenland,” Larsen told Gizmodo.
“In other words, it was a coincidence that the crater was discovered.”
It is now considered to be the “first large crater to be discovered beneath a continental ice sheet.”
Aerial studies were not enough to complete a detailed analysis of the crater. In 2016, a wideband ground-penetrating radar was sent in and the group gathered more data as a result. Using the data, the researchers tried to establish what made the crater.
“When the results came through from the chemical analysis, they were certainly unexpected,” explained study co-author Dr. Iain McDonald, from Cardiff University’s School of Earth and Ocean Sciences.
“Initially we thought we might find the signature from a chrondritic or ‘stoney’ meteorite but the only explanation for the pattern of metals that we found had to be a mixture between the crustal rocks in the surrounding area and an unusual iron asteroid.”
In the end, the researchers determined that it was a “fractionated iron asteroid.” However, the researchers are now aiming to narrow down the estimated date of impact.
“The next step in the investigation will be to confidently date the impact,” said Professor Kurt H Kjær, lead author of the research from the Natural History Museum of Denmark.
“This will be a challenge because it will probably require recovering material that melted during the impact from the bottom of the structure, but this is crucial if we are to understand how the Hiawatha impact affected life on Earth.”