There will be a Lunar Eclipse on Tuesday, December 21st, which is also the Winter Solstice–the shortest day of the year.
A Lunar Eclipse (which differs from the more dramatic Solar Eclipse) is where the Moon passes through the shadow created by the Earth coming between the Earth and the Moon.
For those in the Eastern time zone, the eclipse will be noticeable a little before 2:00 AM Tuesday, will appear earlier as viewers are farther west, and will disappear about three hours later. Totality will last about an hour, so if your sky is clear you should be able to get a great view.
If you’re planning to dash out for only one quick look - it is December, after all - choose this moment: 03:17 am EST (17 minutes past midnight PST). That’s when the Moon will be in deepest shadow, displaying the most fantastic shades of coppery red.