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Robert Quimby

チャンネル登録者数 14.4万人

8929万 回視聴 ・ 3975898いいね ・ 2024/10/01

Solar Analemma #timelapse #astronomy

One picture of the Sun in the West every 24 hours for a year. Watch as the Sun traces out a figure 8 in the sky. The shape of this path is known as the solar analemma.

Why does the position of the Sun change each day? The Earth spins and revolves around the Sun, but the Earth's spin is tilted compared to its orbit. In June the Earth's North Pole tilts toward the Sun, and in December it tilts away. This makes the Sun appear to shift North and South from one day to the next and creates the north-south motion in the analemma.

It takes the Earth about 23 hours and 56 minutes to spin once, but because it is also moving in its orbit, the Earth has to spin a few minutes more for the same side to face the Sun. This is why the average solar day is 24 hours. The Earth's orbit is elliptical, and the Earth moves faster in its orbit when it is closer to the Sun. So sometimes the Earth has to spin for more than 24 hours to return the same side to face the Sun, and sometimes it takes less time. This creates the east-west motion in the analemma.

This video was made from a series of pictures taken by the HPWREN cameras at the Mount Laguna Observatory in San Diego County.

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