Callanish Stones上的8字曲线
(原标题: Analemma over the Callanish Stones)
2022-09-18
浏览次数: 13
如果你每天在同一时间出去，拍一张包括太阳的照片，太阳的位置会如何变化？对这个问题更直观的答案是8字曲线，这是一年中在同一时间从同一地点拍摄的合成图像。这幅特色的八字曲线是由每隔几天在英国苏格兰外赫布里底群岛Callanish村附近的中午拍摄的照片组成的。前景是卡拉尼什石，一个建于公元前2700年人类青铜时代的石圈。目前尚不清楚卡拉尼什石的位置是否具有天文学意义。这个和所有八字曲线呈8字形的最终原因是地轴的倾斜和地球绕太阳轨道的椭圆性。在至日，太阳将出现在八字曲线的顶部或底部。这张特色图片是在12月至日附近拍摄的，所以太阳出现在底部。然而，春分点对应的是八字曲线的中点，而不是交点。本周五凌晨1点04分（美国时间周四）是春分（“平等的夜晚”），此时地球上的白天和黑夜都是平等的。许多文化在春分时庆祝季节的变化。探索你的宇宙：随机APOD生成器
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If you went outside at the same time every day and took a picture that included the Sun, how would the Sun's position change? A 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 analemma was composed from images taken every few days at noon near the village of Callanish in the Outer Hebrides in Scotland, UK. In the foreground are the Callanish Stones, a stone circle built around 2700 BC during humanity's Bronze Age. It is not known if the placement of the Callanish Stones has or had astronomical significance. The ultimate causes for the figure-8 shape of this and all analemmas are the tilt of the Earth axis and the ellipticity of the Earth's orbit around the Sun. At the solstices, the Sun will appear at the top or bottom of an analemma. The featured image was taken near the December solstice and so the Sun appears near the bottom. Equinoxes, however, correspond to analemma middle points -- not the intersection point. This coming Friday at 1:04 am (UT) -- Thursday in the Americas -- is the equinox ("equal night"), when day and night are equal over all of planet Earth. Many cultures celebrate a change of season at an equinox. Explore Your Universe: Random APOD Generator
© Giuseppe Petricca