Before defining what a light-year is, we should define what a light-year is not: It is not a measure of time, but rather a ...

The Voyager spacecraft, Voyager 1 and 2, have traveled farther than any human-made objects in history, entering interstellar ...

When Voyager 1 and 2 crossed the boundary of the heliosphere, many believed they would drift silently into a cold, empty ,voidinterstellar space. It was expected to be a lifeless region, too sparse ...