A meteorite that fell to earth in the US earlier this summer is millions of years older than our planet, scientists studying it have said. There were multiple reports in southern states of a fireball in the sky in broad daylight on June 26. After breaking up in the atmosphere, a plump-tomato sized meteor fragment struck the roof of a home in the city of McDonough, south of Atlanta.
The fragment of the space rock, dubbed the McDonough Meteorite due to the ZIP code it was found in, blew a golf-ball-sized hole through the ceiling and dented the floor. Scientists at the University of Georgia (UGA) have since determined the meteor is likely billions of years old.
Scott Harris, a researcher in the UGA Franklin College of Arts and Sciences’ department of geology, said in a press release on Friday: “This particular meteor that entered the atmosphere has a long history before it made it to the ground of McDonough, and in order to totally understand that, we actually have to examine what the rock is and determine what group of asteroids it belongs to.”
Though the object that struck the home was small in size, Harris emphasised the staggering speed they travel at.
“When they encounter Earth, our atmosphere is very good at slowing them down,” Harris said.
“But you’re talking about something that is double the size of a 50-caliber shell, going at least 1 kilometer per second. That’s like running 10 football fields in one second.”
UGA got their hands on 23 grams of the 50 recovered from the fragment that struck the house and used optical and electron microscopy to analyse the fragments.
Harris says he believes it to be a Low Metal (L) ordinary Chondrite, some of the oldest objects in the solar system.
That classification means he expects it to have formed “some 4.56 billion years ago in the presence of oxygen — older than the Earth itself”, the press release says.
Harris said it “belongs to a group of asteroids in the main asteroid belt between Mars and Jupiter that we now think we can tie to a breakup of a much larger asteroid about 470 million years ago”.
“But in that breakup, some pieces get into Earth-crossing orbits, and if given long enough, their orbit around the sun and Earth’s orbit around the sun end up being at the same place, at the same moment in time.”
McDonough is the 27th meteorite recovered in Georgia in recorded history. Harris said: “This is something that used to be expected once every few decades and not multiple times within 20 years.
“Modern technology in addition to an attentive public is going to help us recover more and more meteorites.”
He’s looking to publish a paper laying out the composition of the rock, as well as its speed and dynamics to help scientists build their understanding of the possible threat posed by much bigger asteroids.
“One day there will be an opportunity, and we never know when it’s going to be, for something large to hit and create a catastrophic situation,” he added. If we can guard against that, we want to.”
