Men have been interested in the stars ever since they first looked up into the sky. Some of these stars may have (1) 1 planets. If that is so, we can suppose that some kinds of (2) 2may exist on one of them. The problem is that the (3) 3 star is four light years away. In other words, light from it has been traveling for four years when it finally (4) 4 . Probably nobody from earth will ever (5) 5 that star because it would take a rocket a hundred thousand years to reach it.