Last week moons made the biggest news in the heavens.
First, NASA released stunning new photos of Europa, one of Jupiter's 16 moons. The pictures, taken by the Galileo spacecraft, showed Europa in amazing detail.
Says scientist James Head: "It's like putting the surface under a microscope."
One picture shows what looks like chunks of ice in seas of slush. Another reveals a 16-mile-wide crater. In one image, icy cliffs soar as high as Mount Rushmore.
The new pictures are exciting to scientists because they offer the best proof yet that Europa holds a liquid ocean under its icy crust. That means Europa has the right ingredients for life as we know it.
Europa is "an incredibly exciting place," says Head. "It has the potential to teach us about the origin of Earth and maybe even life."
Closer to home, scientists announced that Lunar Prospector, launched in January, has found proof of water ice on Earth's moon. "We are certain there is water there," said NASA's Alan Binder.
The discovery means that it would be quite possible to build a base for humans on the moon. Water on the moon, says scientist William Feldman, "will allow a modest amount of colonization."