You may have noticed the Moon exhibiting a ghostly glow lately, where a subtle light is illuminating the usually unlit portion of the lunar surface. This is a phenomenon called Earthshine, and it can be a spectacular sight, not to mention a great opportunity for lunar photography.
Weather permitting, you can see Earthshine this evening, 22 May, after sunset (8:56pm BST in London, 8:13pm EDT in New York City).
Earthshine is visible in the mornings a few days before the new Moon, and in the evenings a few days after the new Moon. You might have already glimpsed it before sunrise on 17 May during the waning crescent phase, but if you didn’t fancy dragging yourself out of bed at that hour, we have another chance during the waxing crescent Moon phase.
Here are the next opportunities to see Earthshine:
21 May: 3.9 per cent illuminated waxing crescent Moon
22 May: 8.9 per cent illuminated waxing crescent Moon
23 May: 15.5 per cent illuminated waxing crescent Moon
What exactly is Earthshine?
Earthshine appears as a soft, subtle glow on the unlit, or ‘night’ portion of the Moon during specific phases. This is when a delicate, but somehow ghostly, shape of the full Moon is nestled in the arc of the bright crescent Moon, and it’s a beautiful sight for these early summer nights.
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