At the south pole of the moon is a giant crater called the South Pole-Aitken Basin, about 2500 kilometres across. It is thought to have been created by a large asteroid striking the moon 4 billion years ago and is among the largest craters in the solar system. Now researchers say the remains of that asteroid may have been found under the lunar surface.
WASHINGTON – Scientists have identified Earth's oldest-known impact crater, and in doing so may have solved a mystery about how our planet emerged from one of its most dire periods. Researchers have determined that the 45-mile-wide (70-km) Yarrabubba crater in Australia formed when an asteroid struck Earth just over 2.2 billion years ago. The collision occurred at a time when the planet was believed to have been encased in ice and the impact may have driven climate warming that led to a global thaw. "Looking at our planet from space, it would have looked very different," said isotope geology professor Chris Kirkland of Curtin University in Australia, one of the researchers in the study published in the journal Nature Communications. "You would see a white ball, not our familiar blue marble."
Japan's space agency said Thursday 10 other smaller man-made craters had been found on an asteroid after its Hayabusa2 space probe produced an artificial crater last month as part of its mission to explore the origin of life and the evolution of the solar system. When the asteroid explorer fired a metal object at the Ryugu asteroid on April 5 to create a crater in the world's first-of-its-kind experiment, scattered fragments of the impactor made other craters, about 1 meter in diameter, the Japan Aerospace Exploration Agency said. The newly discovered craters along with the initial one found earlier -- which is about 10 meters in diameter and 2 to 3 meters in depth -- are expected to help the agency examine the surface of the asteroid and estimate its age, according to JAXA. The agency will continue to investigate the surface of Ryugu, around 340 million kilometers from Earth, in the hope that by June it will have found a suitable site for Hayabusa2 to collect more surface samples following the first such procedure in February. Launched in December 2014 from the Tanegashima Space Center in southwestern Japan, Hayabusa2 reached Ryugu last June and is scheduled to return to Earth around the end of 2020 after completing its mission.
It collided with the force of 10 billion nuclear bombs and dug deep into the Earth's crust, rippling through thick layers of stone and sand like a pebble slamming the surface of a lake, casting material from what was once solid ground high into the sky above. Some of that material put a haze over the sun, chilling the planet and making plants and food scarce. That set into motion a chain of events that would kill all non-avian dinosaurs (we still have birds) and 75 percent of the species alive on Earth at the time. But it also paved the evolutionary way for the rise of mammals, humans included. It was an extraordinary, planet-changing event.