The Expanding Universe

If you go out on a clear, moonless autumn night and look up to the constellation Andromeda, your eyes may catch a glimpse of a faint, diffuse smudge of light. In appearance it cannot compete with some of the more spectacular sights of the sky, such as the surface of the moon or the rings of Saturn, and even a telescope will not reveal much detail: you can make out the outline of an elliptical structure with a central condensed core, but that is about all. Yet before you dismiss this object as insignificant, stop and think: you are looking at the Great Nebula in Andromeda, a sister galaxy to our own Milky Way which, at a distance of 2,000,000 light-years, is the farthest object the unaided human eye can see. To all purpose and extent, you are looking at infinity.1