A full lunar eclipse on a winter's night. From the Bilder-Atlas der Sternenwelt, ca. 1888 [Image source: Wikipedia Commons]
If you haven't heard about it already, this evening (Monday, December 20th) and the wee hours of tomorrow morning will collectively play host to an interesting convergence of three astronomical phenomenon: The winter solstice, the Full Cold Moon of December, and a total lunar eclipse.
The winter solstice (literally, "sun stop") marks that point in time when the sun's apparent southerly traversal along the horizon halts before it reverses direction. This winter, the solstice takes place on Tuesday, December 21st, at 6:38 PM EST -- not actually at the same time as the eclipse, but on the same day, nonetheless.
Tonight (Monday, December 20th), the moon rises just before dusk, at 3:39 PM EST, and the initial (partial, or penumbral) stages of the eclipse begin around 1:32 AM EST on Tuesday morning. The eclipse will then begin to enter its stage of totality around 2:40 AM EST, with complete totality being achieved around 3:17 AM EST. Truly inconvenient for us easterners, but hopefully a little more agreeable timing for those of us closer to the west coast!
Finally, the moon officially becomes full at 3:13 AM EST on Tuesday morning, a mere 4 minutes before complete totality occurs. This particular full moon is known as the Full Cold Moon, a name that goes back to early Native American tribes of the northeast. In fact, each full moon of the year has a traditional name, generally descriptive of the season, and often related to planting or the conditions of the food supply at the time; for example, Full Harvest, Full Snow (or Full Hunger), Full Sturgeon, Full Buck, and Full Hunter, to name a few. An full listing and description of all the full moon names can be found at Farmer's Almanac.
Also, the National Geographic Society has published this excellent article on tonight's eclipse. Apparently, the last time this happened was back in 1638!
So, hopefully, skies will be clear, and temperatures not too inhospitable, for good viewing in your neck of the woods. Get yourself a flask of hot cider and some warm clothes, and get out there and enjoy the view!
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