乌克兰上空的太阳八字曲线 - 天之星天文论坛(大陆著名天文论坛）

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

Explanation: If you took a picture of the Sun at the same time each day, would it remain in the same position? The answer is no, and the shape traced out by the Sun over the course of a year is called an analemma. The Sun's apparent shift is caused by the Earth's motion around the Sun when combined with the tilt of the Earth's rotation axis. The Sun will appear at its highest point of the analemma during summer and at its lowest during winter. Analemmas created from different Earth latitudes would appear at least slightly different, as well as analemmas created at a different time each day. The analemma pictured to the left was built up by Sun photographs taken from 1998 August through 1999 August from Ukraine. The foreground picture from the same location was taken during the early evening in 1999 July.

解释：如果你每天都在同一时间对太阳拍一张照片，太阳还会在同一位置吗？答案是不会，太阳一年中运行的轨迹叫做太阳的八字曲线。太阳的这种轨迹是由地球的绕日运动和地球倾斜的自传轴共同造成的。太阳在夏天会出现在八字曲线的最高点，在冬天则出现在最低点。地球上不同纬度所形成的八字曲线会稍微有点不同，就像每天不同时间所形成的八字曲线一样。图中的照片是从1998年8月到1999年8月在乌克兰拍到的太阳照片合成的。近景照片则是在1999年7月黄昏期间的同一地点拍的。