A team of physicists believe they may have found evidence there were pools of liquid on the Moon at one point.
This could provide proof aliens once thrived there as water is the key ingredient for life to develop.
The Japanese and German experts made the discovery after examining 13 lunar meteorites using state-of-the-art microscopes.
One of the space rocks, called NWA 2727, was found to contain a quantity of moganite, a mineral containing silicon dioxide.
An unnatural protrusion stands out on the surface
The substance has only ever formed on Earth when alkaline liquids become trapped under high pressures.
The bombshell discovery was published in the Science Advances journal this week and shed light on the many mysteries of the moon.
Apollo 17 prepares for take-off on December 7 1972
In April, it was revealed moon-walker Buzz Aldrin passed a lie-detector test when he was being quizzed about an alien encounter.
The astronaut, who is now 88, was the second human ever to set foot on the lunar surface after Neil Armstrong on the Apollo 11 mission.
He claimed to have seen a UFO on his way to the moon, saying: “There was something out there that was close enough to be observed, sort of L-shaped.”