保护地球，探索宇宙，发现文明
2023年9月23日 Afternoon Analemma Image Credit & Copyright: Ian Griffin (Otago Museum) Explanation: An analemma is that figure-8 curve you get when you mark the position of the Sun at the same time each day for one year. To make this one, a 4×5 pinhole camera was set up looking north in southern New Zealand skies. The shutter was briefly opened each cl...
2022年10月10日 A Double Lunar Analemma over Turkey Image Credit & Copyright: Betul Turksoy Explanation: An analemma is that figure-8 curve you get when you mark the position of the Sun at the same time each day for one year. But the trick to imaging an analemma of the Moon is to wait bit longer. On average the Moon returns to the same position in the sky a...
2022年7月2日 Solargraphic Analemmas Image Credit & Copyright: Dawid Rycabel (Pinholove) Explanation: For the northern hemisphere June 21 was the summer solstice, the Sun reaching its northernmost declination for the year. That would put it at the top of each of these three figure-8 curves, or analemmas, as it passed through the daytime sky over the village...
2022年6月21日 Analemma over Taipei Image Credit & Copyright: Meiying Lee Explanation: 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 of images taken at the same time and from the same place over the course of a year. The featured analemma was compiled at 4:30 pm ma...