The Atacama Desert in Chile is shrouded in mystery. The home of massive symbols whose meaning has faded with the passage of time, as well as small, alien-like skeletons whose stories have just lately been uncovered. Its planet is as barren as Mars’s dirt, but it is also rich in gold, silver, and some of the world’s most unusual ecosystems.
That is not the only riddle strewn over the Atacama’s land. For years, experts puzzled by the origins of a 75-kilometer (46.6-mile) long passageway littered with shards of black and green glass. The fragments, which measure up to 50 centimeters (19.7 inches) across, appear to have twisted into their varied shapes by an unknown force.
Researchers believe they have uncovered the answer in a recent report published in the journal Geology: an erupting cosmic fireball that burned the Atacama with such ferocity that the earth forged into the glass.
“This is the first time we’ve seen unambiguous evidence of glasses on Earth caused by heat radiation and winds from a fireball erupting close above the surface,” said Pete Schultz, the paper’s lead author. “This was a genuinely big explosion with such a dramatic effect over such a vast region.” “Many of us have seen bolide explosive fireballs race across the sky, but those are little blips in comparison,” he remarked.
This is not the first theory about what caused the glass fragments: prior studies have hypothesized that the culprit might have been old grass fires from a time when the desert was rich with flora. However, the scientists discovered a few pieces of evidence in the latest study that ruled that out.
The makeup of the shards itself is perhaps the most fascinating piece of evidence for the new interplanetary interpretation. Rather of constructed entirely of one sort of substance, as one might assume from a grass fire, the glass closely resembles the dirt around it, with a few alien additives. The report finds that “every sample studied thus far […] included hundreds of alien mineral grains and rock shards […] uncharacteristic of the native sediments.” The scientists discovered minerals such as cubanite, troilite, and calcium-aluminum-rich inclusions in the glass pieces, which match samples returned by NASA’s comet study mission Stardust.
“Those minerals are what tell us this object has all the hallmarks of a comet,” said Scott Harris, a study co-author. “Having the same mineralogy entrained in these glasses as we discovered in the Stardust samples is pretty strong proof that what we’re seeing is the product of a cometary airburst.”
There is still a lot of work to do to learn more about the explosion: the magnitude and date of the blast, for example, have still to be determined – and any guesses researchers may make in this area simply add to the mystery. “It’s too early to tell if there was a causative link or not,” Schultz said. “What we can say is that this event did occur around the same period as when we think the megafauna vanished, which is fascinating.” “It’s also possible that this was observed by early settlers who had recently arrived in the area.” It would have been a spectacle.”
