If you could lick the surface of Jupiter's icy moon Europa, you would actually be sampling a bit of the ocean beneath. So says Mike Brown, an astronomer at Caltech. Brown and Kevin Hand from the Jet Propulsion Laboratory (JPL) have found the strongest evidence yet that water from the vast liquid ocean beneath Europa's frozen exterior actually makes its way to the surface.

Look up at the night sky and you'll see stars, sure. But you're also seeing planets—billions and billions of them. At least. That's the conclusion of a new study by astronomers at the California Institute of Technology (Caltech) that provides yet more evidence that planetary systems are the cosmic norm. The team made their estimate while analyzing planets orbiting a star called Kepler-32—planets that are representative, they say, of the vast majority in the galaxy and thus serve as a perfect case study for understanding how most planets form.