Did you hear they found water on the Moon? Or was it Mars? No wait, Mercury? An asteroid? It seems like every time there’s big news from outer space, it’s that we found water some place—as traces of ice or wisps of vapor, embedded in rocks or bound up in dry-as-dirt-regolith. What’s so special about a few molecules of H20 trapped in the ground millions of miles away? How do we even spot that from Earth? Today, Matt, Nick, and Emily explore how we search for wet spots in the solar system, what they can tell us about our home planet, and why they’re the key to making our way in the universe. Today on AirSpace: Water—where is it and why we care?