PENNSYLVANIA, USA — Ever notice that when you gaze upon a crescent moon, you can see a dark circle inside it. What is it?
It's actually the moon, believe it or not, and it's a phenomenon called Earthshine.
Earth's bright light, just like the moon's bright light, goes out into space.
When moonlight's coming down onto the Earth during a full moon phase, everything around you looks somewhat illuminated.
Now the same is true of the moon.
If you were standing on the moon during a crescent phase and you were looking back at the Earth, you would see nearly a fully illuminated Earth in front of you.
It's Earth's light back up towards the moon that partially illuminated that darkened portion of the moon. So you see that little thin crescent.
Then Earth's light goes back out to the moon that creates that dark outline that you can just barely make out.
Later this week, the moon will be in a waning crescent phase. So, check it out.
See past Skywatch 16 segments on YouTube.