数码月食
(原标题: A Digital Lunar Eclipse)
2022-05-19
浏览次数: 13
这张拍摄于5月15日至16日的照片是在佛罗里达州中部晴朗的天空中，随着月全食期间的满月在树梢上方形成弧线而拍摄的。数码相机每5分钟拍摄一张画面，显示了日食在三个小时内的过程。明亮的月盘在穿过地球的阴影时变暗变红。事实上，计算出这个序列的中心框架，可以测量出这次日食的总阶段大约90分钟的持续时间。公元前270年左右，希腊天文学家阿里斯塔克斯也测量了月全食的持续时间，但可能没有数字手表和相机的帮助。尽管如此，他还是利用几何学设计了一种简单而又令人印象深刻的精确方法，根据月食持续时间计算出月球与地球半径的距离。
查看原文解释
Recorded on May 15/16 this sequence of exposures follows the Full Moon during a total lunar eclipse as it arcs above treetops in the clearing skies of central Florida. A frame taken every 5 minutes by a digital camera shows the progression of the eclipse over three hours. The bright lunar disk grows dark and red as it glides through planet Earth's shadow. In fact, counting the central frames in the sequence measures the roughly 90 minute duration of the total phase of this eclipse. Around 270 BC, the Greek astronomer Aristarchus also measured the duration of total lunar eclipses, but probably without the benefit of digital watches and cameras. Still, using geometry he devised a simple and impressively accurate way to calculate the Moon's distance in terms of the radius of planet Earth, from the eclipse duration.
© Michael Cain