Dear Tom,
How do lunar phases differ in the polar regions? Are there 24 hours of moonlight during the full darkness of winter?
David Labotka, Westmont
Dear David,
You are exactly right. Around the full moon, there are 24 hours of moonlight at very high latitudes when there is winter darkness. At full moon, the moon is opposite the sun in the sky. Since the sun, moon and Earth are about in line at that time, the full moon closest to the winter solstice would occupy about the same place in the sky as the sun at the summer solstice, and would be above the horizon for 24 hours. Even in Chicago, a full winter moon is especially bright since it is so high in the sky at midnight–about the same elevation as the summer sun is at noon. On a clear winter night, lunar brightness can be enhanced by the reflection from a fresh covering of snow.
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Tom Skilling is chief meteorologist at WGN-TV. His forecasts can be seen Monday through Friday on WGN News at noon and 9 p.m.
Write to: ASK TOM WHY, 2501 Bradley Place, Chicago, IL 60618 or asktomwhy@wgntv.com (Mail volume precludes personal response.)
