Earth’s Oldest Asteroid Impact is Two Billion Years Old

The oldest asteroid collision on the planet, the Yarrabubba impact crater in Western Australia, is a whopping 2.229 billion years old. After analyzing minerals at the crater site, researchers have found the asteroid hit at the end of an era called Snowball Earth (one of the planet’s ice ages). Scientists, led by Dr Timmons Erickson (a geochronologist at Houston’s NASA Johnson Space Center), studied around 200 pounds of rocks from the site and calculated the age of the crater on the “measurements of 39 zircon and monazite crystals.” The ballpark for uncertainty in those 2.229 billion years is just five million, and “the next oldest-oldest impact structure Vredefort Dome in South Africa is over 200 million years younger.” While the crater is no longer visible, and no topography signposts its existence, it still holds our planet’s secrets deep inside. Find out more at the New York Times.