Mysterious shards of GLASS strewn across the Atacama Desert were likely created by an ancient exploding comet, study claims
Mysterious shards of glass strewn across Chile's Atacama Desert were likely created by an ancient exploding comet, a study has claimed.
The pieces of dark green or black glass, which came to scientists' attention a decade ago, are clustered in a vast corridor that stretches almost 50 miles (75km) across.
Some are up to 20 inches (50cm big) and look as if they've been folded and twisted into their current forms.
It had been thought they could have been created by volcanic activity or ancient grass fires — because the region wasn't always a desert — but new research led by Brown University has come to a different conclusion.
The study discovered that the glass contained tiny fragments with minerals often found in rocks of extraterrestrial origin.
Discovery: Mysterious shards of dark green or black glass strewn across Chile's Atacama Desert (pictured) were likely created by an ancient exploding comet, a new study has claimed
The pieces of dark green or black glass, which came to scientists' attention a decade ago, are clustered in a vast corridor that stretches almost 50 miles (75km) across
Out of this world: The fragments of glass contain exotic minerals such as cubanite and troilite (pictured) only found in meteorites and other extraterrestrial rocks, the researchers said
Those minerals closely match the composition of material returned to Earth by NASA's Stardust mission, which sampled the particles from a comet called Wild 2, the authors said.
They concluded that the minerals are likely the remains of an extraterrestrial object — most likely a comet — streamed down after an explosion that melted the sandy surface below.
'This is the first time we have clear evidence of glasses on Earth that were created by the thermal radiation and winds from a fireball exploding just above the surface,' said the study's lead author Pete Schultz, of Brown University.
'To have such a dramatic effect on such a large area, this was a truly massive explosion.
'Lots of us have seen bolide fireballs streaking across the sky, but those are tiny blips compared to this.'
Researchers collected more than 300 samples of the desert glass before examining them under an electron microscope and analysing their chemical composition through spectroscopy.
The samples showed evidence of having been twisted, folded, rolled and even thrown while still in molten form.
According to the researchers, that is consistent with a large incoming meteor and airburst explosion, which would have been accompanied by tornado-force winds.
They added that the glass fragments 'indicate nearly simultaneous (seconds to minutes) intense airbursts close to Earth's surface near the end of the Pleistocene' 12,000 years ago.
The glass is in patches across the Atacama Desert east of Pampa del Tamarugal, a plateau in northern Chile nestled between the Andes to the east and Chilean Coastal Range to the west
The minerals closely match the composition of material returned to Earth by NASA's Stardust mission, which sampled the particles from a comet called Wild 2, the authors said
Researchers collected more than 300 samples of the glass before examining them under an electron microscope and analysing their chemical composition through spectroscopy
Minerals in the glass called zircons thermally decomposed to form baddeleyite, the authors said, which would have required extremely hot temperatures of above 3,038°F (1,670°C)
During the Pleistocene epoch, there were fertile patches in the desert with trees and grassy wetlands created by rivers extending from mountains to the east.
It had been suggested that widespread fires may have burned hot enough to melt the sandy soil into large glassy slabs.
But the amount of glass present, along with several key physical characteristics, make this theory extremely unlikely, the new research found.
Minerals in the glass called zircons thermally decomposed to form baddeleyite, the authors said, which would have required extremely hot temperatures of above 3,038°F (1,670°C), which is far hotter than a wildfire.
The glass is concentrated in patches across the Atacama Desert east of Pampa del Tamarugal, a plateau in northern Chile nestled between the Andes mountains to the east and the Chilean Coastal Range to the west.
It contains exotic minerals such as cubanite and troilite only found in meteorites and other extraterrestrial rocks, the researchers said.
'Those minerals are what tell us that this object has all the markings of a comet,' said co-author Scott Harris, a planetary geologist at the Fernbank Science Center.
'To have the same mineralogy we saw in the Stardust samples entrained in these glasses is really powerful evidence that what we're seeing is the result of a cometary airburst.'
The pieces of dark green or black glass are clustered in a vast corridor that stretches almost 50 miles (75km) across Chile's Atacama Desert (stock image)
Researchers said more work is needed to establish the exact age of the glass, which would then help determine when the ancient comet exploded in the Atacama Desert (pictured)
Pictured is an artist's impression of the Stardust spacecraft approaching comet Wild 2 in 2004More work needs to be done to establish the exact age of the glass, which would determine exactly when the event took place, Schultz said.
But experts believe the impact happened around the time large mammals disappeared from the region.
'It's too soon to say if there was a causal connection or not, but what we can say is that this event did happen around the same time as when we think the megafauna disappeared, which is intriguing,' Schultz said.
'There's also a chance that this was actually witnessed by early inhabitants, who had just arrived in the region. It would have been quite a show.'
The research has been published in the journal Geology.
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