If you’ve ever peered at a full moon through a telescope you’ve probably noticed a star or two near the edge. You’ll notice the Moon moving with respect to the star — evidence of the Moon’s rapid movement around the Earth, and even our own globes fast spin on its axis. If you monitor the orbiting globe for only a few minutes you might see that star drift behind it.

The moon often blocks, or occults, stars from our view. And human beings have been watching since Aristotle recorded the Moon covering Mars on April 4, 357 B.C. Sky & Telescope will help you know when these occultations are going to occur. And we’ll walk you through how your own observations may provide valuable scientific data, which may further map the luminous landscape hundreds of thousands of miles away.