Before there were trees, when the Earth was inhabited only by single-celled organisms, the largest asteroid to hit our planet landed near what we now know as Johannesburg, South Africa, forming the Vredefort crater.
With an estimated crater size between 155 to 174 miles at first impact, the size of the asteroid was originally estimated to be around 9.3 miles in diameter.
However, new research from the University of Rochester suggests that the recalculated size was about 15.5 miles, according to a study published in the Journal of Geophysical Research: Planets.
The team used a shock physics program called Simplified Arbitrary Langrangian Eulerian (iSALE) to calculate the size of the asteroid needed to create an impact on the scale of the Vredefort crater.
They found that the original diameter estimate would produce an impact site measurement of about 75.8 miles. To arrive at the actual number of 106-174 miles, the impactor would have to have been much larger.
Estimates of the effect this impact may have had on the environment of the Earth can be drawn from what we already know about the aftermath of the Chicxulub crater impact.
Thought to have caused the mass extinction of the dinosaurs, the Chicxulub crater was created by an asteroid from 6.2 miles that wiped out 75 percent of plant and animal species on Earth ago 66 millions of years.