One of the Moon's biggest craters created by an asteroid more than 150 miles across

The asteroid, so big it could be classified as a protoplanet created one of the Moon's biggest craters. An asteroid had more than 250km (150 miles) across, a study suggests.
It smashed into the lunar surface about 3.8 billion years ago, forming Mare Imbrium - the feature also known as the right eye of the "Man in the Moon".
Scientists say the asteroid was three times bigger than previously estimated and debris from the collision would have rained down on the Earth.
The Imbrium crater measures more than 1,200km (750 miles) across. Until now, scientists used computer models to estimate the size of the asteroid that led to its formation. But for in a new assessment of the collision, researchers recreated the smash in the lab. Using a three-storey-high, hyper-velocity gun, they fired small spheres of metal travelling at more than 22,000km per hour (13,000 mph) into a curved aluminium plate.

http://www.bbc.com/news/science-environment-36847382

Research: http://www.nature.com/nature/journal/v535/n7612/full/nature18278.html