Sunset Analemma
Image Credit & Copyright: MarcellaGiulia Pace
Explanation: Today, the solstice is at15:54 Universal Time, the Sun reaching the northernmost declination in itsyearly journey through planet Earth's sky. A June solstice marks theastronomical beginning of summer in the northern hemisphere and winter in thesouth. It also brings the north's longest day, the longest period betweensunrise and sunset. In fact the June solstice sun is near the top, at the most northernpoint in the analemma or figure 8 curve traced by the position of the Sun inthis composite photo. The analemma was created (video) from images taken every10 days at the same time from June 21, 2018 and June 7, 2019. The time waschosen to be the year's earliest sunset near the December solstice, so theanalemma's lowest point just kisses the unobstructed sea horizon at the left.Sunsets arranged along the horizon toward the right (north) are centered on thesunset at the September equinox and end with sunset at the June solstice.
落日时分的日行迹
就在6月21日，世界时间15点54分夏至来临之时，太阳在其每年穿过地球上空的旅程中到达北回归线的位置。在天文学上，夏至标志着北半球夏天和南半球冬天的开始。夏至也是北半球白昼时间最长的一天。实际上，夏至的太阳位于这幅合成图像的顶部附近，也就是由太阳位置绘制的日行迹或8字曲线最北点。这道日行迹是由从2018年6月21日到2019年6月7日间，每十天在同一时间拍摄的图像组合而成。拍摄时间被选择为一年中日落时间最早的冬至附近，因此日行迹的最低点正好与影像左侧一览无余的海平面相接。沿地平线向右（北）分布的落日以秋分的落日点为中心，以夏至的落日为结束点。
参考文献：
https://apod.nasa.gov/apod/image/1906/AnalemmaSunset.jpg
近期文章：
Astronomy Picture of the Day——我们银河系的磁心
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