Where did the water we believe is on the Moon come from? Most scientists think they know the answer - from the solar wind. They believed the hydrogen atoms that make up the solar wind bombarded the lunar surface, which is made up primarily of silica. When that hydrogen hits the oxygen atoms in that silica, the oxygen is sometimes released and freed to bond with the incoming hydrogen, which in some cases creates water. But no one has ever attempted to replicate that process to prove its feasibility. A new paper by Li Hsia Yeo and their colleagues at NASA's Goddard Space Flight Center describes the first experimental evidence of that reaction.