自转地球上的冬至
(原标题: Solstice on a Spinning Earth)
2025-12-21
浏览次数: 1528
你能从地球倾斜的角度看出今天是冬至日吗？是。在冬至日，地球的明暗分界线——昼夜分界线——倾斜得最大。这个特色的延时视频通过在12秒内展示地球上的一整年来证明这一点。从地球同步轨道上，气象卫星9号每天在当地同一时间记录下地球的红外图像。视频开始于2010年9月的春分，终点线是垂直的：春分。当地球围绕太阳旋转时，人们看到明暗分界线以某种方式倾斜，从而减少了北半球每天的阳光照射，导致北方进入冬季。在最倾斜的地方，冬至出现在北方，夏至出现在南方。随着时间的推移，2011年3月的春分在视频中途到来，随后明暗分界线向另一个方向倾斜，导致南半球进入冬季，北半球进入夏季。拍摄到的这一年又以9月的春分结束了，地球已经绕太阳转了几十亿圈，也将绕太阳转几十亿圈。APOD回顾：RJN的夜空网络讲座
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Can you tell that today is a solstice by the tilt of the Earth? Yes. At a solstice, the Earth's terminator -- the dividing line between night and day -- is tilted the most. The featured time-lapse video demonstrates this by displaying an entire year on planet Earth in twelve seconds. From geosynchronous orbit, the Meteosat 9 satellite recorded infrared images of the Earth every day at the same local time. The video started at the September 2010 equinox with the terminator line being vertical: an equinox. As the Earth revolved around the Sun, the terminator was seen to tilt in a way that provides less daily sunlight to the northern hemisphere, causing winter in the north. At the most tilt, winter solstice occurred in the north, and summer solstice in the south. As the year progressed, the March 2011 equinox arrived halfway through the video, followed by the terminator tilting the other way, causing winter in the southern hemisphere -- and summer in the north. The captured year ends again with the September equinox, concluding another of the billions of trips the Earth has taken -- and will take -- around the Sun. APOD Review: RJN's Night Sky Network Lecture