“As bright as the moon looks in the night sky, what we’re really seeing is sunlight, and the percent of its face that’s illuminated depends on where it is in relation to the Earth. At the point in its orbit when the moon at its closest point to the sun, we see, or rather don’t see, a New Moon. At the point in its orbit when the moon is farthest from the sun, we get a full moon.
But if the Earth is sitting here in the middle, why doesn’t Earth cast a shadow during every full moon?”
Joe Hanson explains lunar eclipses in this episode of It’s Okay to Be Smart. Pair the above with Does The Moon Really Orbit The Earth? (Yes, but wow, this question jumpstarts layers of interesting information.) Watch:
Related reading: Hill sphere.
Next: watch time lapse and real time videos of a lunar eclipse.