Now We Know the Distance Between Stars

Here's an astronomer's quote to try to wrap your head around, courtesy of PhysOrg: "The optical and ultraviolet light from stars continues to travel throughout the universe even after the stars cease to shine, and this creates a fossil radiation field we can explore using gamma rays from distant sources." How this exploration of cosmic "fog," or "extragalactic background light," might apply to real life: If you're in a bar and somebody bets that you don't know the average distance between stars, say 4,150 light-years and collect your money. The LA Times has more on how the new measurement came to be, thanks to NASA's Fermi Gamma-ray Space Telescope. (More outer space stories.)