According to NASA, the impact left behind a widespread "double crater" which was found by its Lunar Reconnaissance Orbiter - meaning it was not an average rocket. NASA knows something crashed into the moon on March 4, but exactly what that something was still remains unknown nearly four months on.
The crash was spotted near the huge Hertzsprung crater on the far side of the moon. NASA experts know it was traveling at roughly 5,7000mph when it struck.
"Since the origin of the rocket body remains uncertain, the double nature of the crater may indicate its identity."
It was previously thought that the hit could have been a leftover from China's Xichang Satellite Launch Center's 2014 launch of a Long March 3C rocket. That rocket took China's Chang'e 5-T1 spacecraft to the moon. However, scientists have ruled that out - so what hit the moon stays a mystery.