New analyses of lunar volcanic glass collected and returned to Earth during the US Apollo missions of the 1960s and 70s indicate that water was once held in the Moon’s interior. This information challenges the prevailing belief that the Moon is a dry planet, created from the debris of a massive collision between Earth and another planet-sized object. Scientists believed that the heat generated by the impact would have vaporized any existing water, but it appears that more than three billion years ago, when these multi-colored volcanic glass pebbles were formed, water was still very much a part of the Moon’s magma.