Nasa crashed two spacecraft into the Moon to try to find out once and for all if there's any water there.
A 2,200kg rocket smashed into the surface and the dust it threw up was collected and analysed.
Scientists have now studied the dust and reckon it contains a significant amount of water-ice and water vapour.
Scientists say this finding is a huge discovery as it could provide a water supply for astronauts on the moon in the future.
Watch an animation of the mission here: