The full moon may hog all the glory, but there’s a quiet, stunning beauty to a moon that is reflecting light from Earth. The phenomenon is called Earthshine, and you have a good opportunity to catch some of its rays in the night sky this month.
NASA described Earthshine as an “eerily beautiful glow” in a November skywatching update. You’ll know you’re seeing it when the dark face of the moon takes on a ghostly gleam. It’s subtle, but sublime.
Earthshine is generated by a game of cosmic ping-pong. Sunlight reflects off of Earth, strikes the moon and bounces back to us. “Changes in the brightness of Earthshine are mainly caused by changes in cloudiness — the cloudier the Earth, the brighter the Earthshine,” said NASA back in 2004.
The best time to enjoy Earthshine is around the new moon, when the usual bright moonshine doesn’t interfere with viewing. It’s especially lovely when the moon sports a slight crescent, highlighting the contrast between bright and dark.
While most people will want to circle Nov. 17-20 on their calendars to go out after sunset and bathe in some Earthshine, there’s an additional viewing opportunity going on through Nov. 12 before dawn. As a bonus on the morning of Thursday the 12th, the moon will make its appearance above Venus. That might be worth getting up early for.
The good news is that even if you miss the Earthshine this month, there will be other opportunities. Now that you know what to look for, you can get more enjoyment out of the new-moon process. Skywatching doesn’t have to be all about the fanfare of a full moon. There’s magic even in the seeming darkness.