Atmospheres, like love, often don't last forever. That's the lesson we astronomers are learning (well, at least, the atmosphere part), as we push outward with our telescopes into a galaxy rich with planets. It's not an insignificant point, since the fate of atmospheres holds the key to science's most enduring question: Are we alone in the universe? Last Monday, I spent the day at Penn State working with James Kasting on how planets can lose their atmospheres into space. Kasting is a great scientist who has spent much of his career exploring what allows a planet to become habitable. In...