How much stuff is in a light-year?

Imagine taking the distance that light travels in an entire year. Now turn that distance into a cube, each side one light-year across. How much "stuff" would be in there? And how empty would it be? It all depends on where you put your massive cube. » 1/31/14 6:40am 1/31/14 6:40am

The stars dance with a spiral galaxy 80 million light-years away

Everything in this image is so far away that it defies our comprehension. And yet we're also looking at two vastly different scales here, as stars from well within our own galaxy share space with a far distant spiral galaxy. » 3/22/11 3:20pm 3/22/11 3:20pm