What is the biggest crater on Earth?
The biggest known is Vredefort in South Africa. It was once about 160 to 300 kilometres across and is about 2 billion years old.
The largest known impact crater on Earth is the Vredefort structure in South Africa, south-west of Johannesburg. It formed about 2 billion years ago, when an asteroid perhaps 10 to 15 kilometres across, or more, smashed into the ground.
Vredefort is so old that wind, rain and rivers have worn most of it away. What you can see today is a ring of hills, called the Vredefort Dome, about 70 to 90 kilometres across, which is the deep, uplifted centre of the original crater. By studying the rocks, scientists estimate that the whole crater was originally somewhere between about 160 and 300 kilometres wide.
Other giant craters include Chicxulub in Mexico, about 180 kilometres across and 66 million years old, which is linked to the end of the dinosaurs, and Sudbury in Canada, about 1.85 billion years old.
Vredefort is now a World Heritage Site. Visitors can see rocks that were squeezed and melted by the impact, including special cone-shaped patterns called shatter cones. It reminds us that Earth has been hit by giant space rocks in the past, but such huge impacts are extremely rare, happening only once in many millions of years.