• The December solstice is when the sun reaches its southernmost point for the year. This year, it happens at 11:12 Universal Time on December 21. Here,

in the mainland United States, the solstice falls on December 21 at 6:12 a.m. EST, 5:12 a.m. CST, 4:12 a.m. MST and 3:12 a.m. PST. Translate to your time zone here.
• On the December solstice, we celebrate the (unofficial) first day of winter in the Northern Hemisphere and first day of summer in the Southern Hemisphere. Unofficial? Yes. Winter and summer start at the solstices by tradition, not official decree.
• Yet these solstices bring very real occurrences to our sky, which you can witness for yourself. In both the Northern and Southern Hemispheres, the December solstice brings the southernmost sunrise and the southernmost sunset of the year. If you stand in one spot day after day, week after week - for example, gazing out a window toward the sunrise or sunset on the horizon - you will surely notice the sunset's northward trek along the horizon over the coming months. From time to time, try fixing a bit of tape to the window on which you've written the date, to help you mark the sun's passage.
• In the Northern Hemisphere, the southernmost sunrise and sunset usher in the year's shortest day and the longest night. In the Southern Hemisphere, it's the exact opposite, for the year's southernmost sunrise and sunset give the Southern Hemisphere its longest day and shortest night.
• Not everyplace worldwide has a sunrise and a sunset on the day of the Decem

ber solstice. North of the Arctic Circle - or north of 66.5 degrees north latitude - there is no sunrise or sunset today, because the sun stays beneath the horizon all day long. South of the Antarctic Circle - at 66.5 degrees south of the equator - you won't see a sunrise or sunset either, because the sun stays above the horizon all day.

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