Ancient asteroid which hit Earth was 15 miles wide

Two billion years ago, an absolutely massive lump of rock slammed into Earth, far bigger than the impact which wiped out the dinosaurs.

The impactor which formed the Vredefort crater in South Africa - thought to have been an asteroid - is far bigger than previously believed, a new study by the University of Rochester has shown.

It crashed into the planet in an area near present-day Johannesburg, South Africa, leaving the world’s biggest impact crater.

The 15-mile-wide object would have had global effects, similar to the one thought to have killed the dinosaurs.

Former Rochester researcher Natalie Allen, now a PhD student at Johns Hopkins University, said, “This could have had a devastating effect on photosynthetic organisms.

“After the dust and aerosols settled, which could have taken anywhere from hours to a decade, greenhouse gases such as carbon dioxide that were emitted from the impact would have raised the global temperature potentially by several degrees for a long period of time.”

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Understanding the impact could help to understand the dangers posed by asteroids, the researchers believe.

Allen says, “Understanding the largest impact structure that we have on Earth is critical. “Having access to the information provided by a structure like the Vredefort crater is a great opportunity to test our model and our understanding of the geologic evidence so we can better understand impacts on Earth and beyond.”

Over the course of two billion years, the Vredefort crater has eroded, making it difficult for scientists to estimate its size at the time of the original impact.

Dust and aerosols from the Vredefort impact would have spread across the planet and blocked sunlight, cooling the Earth’s surface,

Scientists have widely accepted, based on previous research, that the impact structure, known as the Vredefort crater, was formed by an object 9.3 miles in diameter that was travelling at a velocity of nine miles per second second - but this is too small for the actual size of the Vredefort crater.

But research showed that the original size of the crater was bigger than previously believed - 155 miles across.

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Allen, Nakajima, and their colleagues conducted simulations to match the updated size of the crater.

Their results showed that an impactor would have to be much larger—up to 15 miles wide —and traveling at a velocity of up to 12 miles per second to explain a crater 155 miles wide.

Miki Nakajima, an assistant professor of Earth and environmental sciences says, “Unlike the Chicxulub impact, the Vredefort impact did not leave a record of mass extinction or forest fires given that there were only single-cell lifeforms and no trees existed two billion years ago.

“However, the impact would have affected the global climate potentially more extensively than the Chicxulub impact did.”

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