We stand, now, in your backyard—your small corner of the vast universe—watching the colorful hues of the setting sun, the sky fading to black velvet, the glow of thousands of stars emerging.

But it's much more than just a pretty scene. Here, you are experiencing the cosmic clockwork in action as the Earth spins eastward and flies forward in its orbit around the sun.

As the Earth moves, the sky changes. And it's easy to lose your way looking for some of the more remarkable objects in the heavens.