A good home for future lunar colonists might be pit craters -- holes in the surface that are part of collapsed lava tubes. The tubes can extend a long way, providing protection from radiation, meteorites, and other hazards. These are three views of a pit crater in the Moon's Marius Hills, taken at different Sun angles. The pit is more than 100 feet deep, and is as wide as a football field. [NASA/GSFC/Arizona State]