Since the beginning of time, our planet has been struck by numerous meteorites. Indeed it is theorised by some that a meteorite impact brought the building blocks of life to Earth. However, our planet is geologically active. These processes alter the generic shapes of impact craters, so the crater marks usually found on other planets are rarely seen on ours. A notable exception to this is Barringer Crater in Arizona.
The largest crater impact on Earth is Vredefort Crater in South Africa measuring 300km (185miles) wide. It also has the honor of being the oldest, dating back to 2.02 billion years ago. The third-largest on the list is Sudbury Crater in Ontario measuring 130km (81miles) across created 1.85 billion years ago.
The second largest is arguably the most significant of the three, the Chicxulub Crater in the Gulf of Mexico measuring 180km (110miles) across. This meteorite impact is believed to have occurred 65 million years ago and is significant as this is the meteorite believed to have caused the extinction of the dinosaurs. Shocked quartz and levels of iridium, a metal common in space found in rocks from this period and at the crater site are proof of this long-ago tragedy. It was estimated that 75% of all life on Earth went extinct due to this meteorite, but fortunately, life rebounded since then.