The Moon is completely dry
The old claim turned out to be wrong and was rejected by evidence.
TaughtApollo samples showed the Moon is bone dry. There is no water there in any form.
NowThere is water ice in permanently shadowed polar craters, confirmed when NASA's LCROSS mission deliberately crashed into Cabeus crater in 2009, and water molecules exist even on the sunlit surface.
What actually happened
The Apollo-era conclusion was based on real evidence: the returned samples were dry. The problem was generalizing from a dozen equatorial landing sites to an entire world.
The Moon's axial tilt is tiny, which means the floors of some polar craters have not seen sunlight in billions of years and sit at around minus 240 degrees Celsius. Anything that drifts in stays. In 2009 NASA sent the spent upper stage of a rocket into Cabeus crater and flew a shepherding spacecraft through the plume, which measured roughly 5.6% water ice by mass. India's Chandrayaan-1 detected hydration signatures the same year. In 2020, NASA's SOFIA airborne observatory detected water molecules on the sunlit surface, which had been thought impossible.
This is the discovery that turned the lunar south pole into the target for Artemis and every other crewed lunar program. Water means drinking water, breathable oxygen, and rocket propellant that you do not have to lift out of Earth's gravity well.
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Sources
- NASA: LCROSS impact confirms water on the Moonscience.nasa.gov
- NASA: Water on the sunlit Moon (SOFIA, 2020)nasa.gov
Who was taught this
Still standard through 2010, so anyone who finished school between 1950 and 2009 learned the earlier version.