An asteroid almost as wide as Rhode Island may have plowed into Earth 3.26 billion years ago, leaving a trace in South Africa’s Barberton greenstone belt. Hitting the planet at a speed of 20 kilometers per second, the 37- to 58-kilometer-wide space rock could have jolted Earth with at least the force of a magnitude 10.8 earthquake and set off tsunamis thousands of meters high, researchers report April 14 in Geochemistry, Geophysics, Geosystems. It is the first time scientists have calculated the scale of the impact and its effects on Earth.