NASA·APOD每日天文一图2022.5.19 [超高清]

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. 

记录于5月15日至16日，这一系列曝光发生在月全食期间的满月之后，当时它在佛罗里达州中部晴朗的天空中的树梢上方形成弧形。数码相机每5分钟拍摄一帧，显示日食在三个小时内的发展过程。明亮的月面在穿过行星地球的阴影时会变得暗红色。事实上，计算序列中的中心帧可以测量这次日食整个阶段大约90分钟的持续时间。大约在公元前270年，希腊天文学家阿里斯塔丘斯（Aristarchus）也测量了月全食的持续时间，但可能没有使用数字手表和相机。尽管如此，他还是利用几何学设计了一种简单而令人印象深刻的精确方法，从日食持续时间开始，根据行星地球的半径计算月球的距离。