A very long time ago, a massive meteor, while entering Earth’s atmosphere, broke into two huge pieces. They were at least 6 miles (10 km) across.
The impacts on the Australian countryside were violent and spanned nearly 250 miles (400 km).
So what’s the difference between an asteroid, a meteor, and a meteorite? These words are mistakenly used interchangeably. A simple explanation is that an asteroid is a rock that is out in space, a meteor is an asteroid that enters the Earth’s atmosphere and creates a fireball as it burns, and if anything is left of a meteor after most of it burns up and it hits the Earth, it’s called a meteorite.
While drilling for a potential geothermal energy project, researchers found the evidence. The craters have been hidden away all this time, due to natural processes. The researchers found that there were layers of quartz that had been shocked (quickly deformed during an impact). After taking a closer look and with some additional testing, they found there was also evidence from much deeper in the Earth’s crust.
World’s largest known asteroid impact found in Australia:
“There are two huge, deep domes in the crust, formed by the Earth’s crust rebounding after the huge impacts, and bringing up rock from the mantle below,” said lead researcher Andrew Glikson, from the ANU School of Archaeology and Anthropology, who published his findings in Tectonophysics.
The Vredefort crater in South Africa was the previous record holder. It measured a diameter of 236 miles (380 km.) Vredefort impact structure still remains the oldest known crater, forming about 2,023 million years ago.
Australian National University on their webpage said: “The two asteroids must each have been over 10 kilometers across – it would have been curtains for many life species on the planet at the time,” said Dr Glikson.
Wondering why no one noticed it? It was because of normal geological processes. Evidence has been worn away over millions of years, and while erosion washed away evidence of the impact on the surface, new layers of rocks where deposited over the top.
Watch Target Earth: the asteroid impact history of Australia, Dr Andrew Glikson, ANU:
Scientists are still trying to work out the exact age of the crater. All the researchers can do is keep examining the rocks around the impact site for clues as to when the impact may have occurred.
Glikson said: “It’s a mystery—we can’t find an extinction event that matches these collisions. I have a suspicion the impact could be older than 300 million years,” reported Popular Science.
It would be good to get more confirmation, but it is a huge discovery.