The official start of astronomical winter \u2014 the winter solstice \u2014 \noccurred at 5:44am the morning of December 21st. The winter solstice is \nthe exact moment that the Northern Hemisphere is tilted the farthest it \never gets from the sun. As a result, December 21st was the longest night\n of the year for the Northern Hemisphere. This is evident by the fact \nthat the true-color imagery we get from the NOAA\/NASA Suomi NPP \nsatellite, which requires visible light, has no return over a large \nportion of the North Pole, as shown in the image from December 21, 2015,\n on the left. Compare this to the image taken on the last summer \nsolstice, June 21, 2016 (right), which shows the North Pole in its \nentirety.<\/p>\n\n\n\n
Although the winter solstice marks the shortest daylight period in \nthe Northern Hemisphere, it\u2019s not the day of the latest sunrise or \nearliest sunset. Most places in the mid-latitudes see their earliest \nsunset two weeks before the solstice, while the latest sunrise is not \nuntil early January. The misalignment is the unique result of the \nEarth\u2019s 23.5-degree tilt and our elliptical orbit around the sun.<\/p>\n\n\n\n