Copyright:
Adrianos Golemis
原文:
Does the Sun return to the same spot on the sky every day? No. A better and more visual answer to that question is an analemma, a composite image taken from the same spot at the same time over the course of a year. The featured weekly analemma was taken despite cold temperatures and high winds near the Concordia Station in Antarctica. The position of the Sun at 4 pm was captured on multiple days in the digital composite image, believed to be the first analemma constructed from Antarctica. The reason the image only shows the Sun from September to March is because the Sun was below the horizon for much of the rest of the year. In fact, today being an equinox, the Sun rises today at the South Pole after a six month absence and won’t set again until the next equinox in March, baring large atmospheric refraction effects. Conversely, today the Sun sets at the North Pole after half a year of continuous daylight. For all of the Earth in between, though, the equinox means that today will have a nighttime and daytime that are both 12 hours long. Follow APOD on: Facebook, Google Plus, or Twitter
中文翻譯:
☀️ 太陽每天會回到天空中的同一位置嗎？不會的。要更直觀地理解這個問題，可以參考「太陽的時間圖」，這是一幅從同一位置以相同時間拍攝一整年的合成圖片。這張每週的太陽時間圖是在嚴寒和強風的南極康科迪亞站拍攝的。圖片顯示的太陽位置是在每天下午4點拍攝的多天合成圖，這被認為是首張來自南極的太陽時間圖。
這張圖片只顯示了從9月到3月的太陽位置，因為在其餘的年份大部分時間裡，太陽都在地平線以下。事實上，今天是春分，南極的太陽在經過六個月的消失後再次升起，並將持續不落至明年春分，當然這裡可能影響到大氣折射效應。相對地，今日北極的太陽則在經過半年的白晝後再次下落。
在地球的其他地方，春分意味著今天的白天和黑夜都是12小時長。
🔭✨ #太陽 #春分 #南極 #康科迪亞 #太陽時間圖 #天空 #自然之美 #天文 #月球 #星空 #探索 #科學 #教育
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來源:NASA每日圖片
