Astronomy Picture of the Day—20190219

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.

2019 February 19

MoonStruck

ImageCredit & Copyright: Petr Horálek

Explanation:Craters produced by ancient impacts on the airless Moon have long been afamiliar sight. But only since the 1990s have observers began to regularlyrecord and study optical flashes on the lunar surface, likely explosionsresulting from impacting meteoroids. Of course, the flashes are difficult tosee against a bright, sunlit lunar surface. But during the January 21 totaleclipse many imagers serendipitously captured a meteoroid impact flash againstthe dim red Moon. Found while examining images taken shortly before the totaleclipse phase began, the flash is indicated in the inset above, near the Moon'sdarkened western limb. Estimates based on the flash duration recorded by theMoon Impact Detection and Analysis System (MIDAS) telescopes in southern Spainindicate the impactor's mass was about 10 kilograms and created a craterbetween seven and ten meters in diameter.

撞击月球

解释：在没有空气的月亮上的古老陨石坑长期以来都是一道熟悉的景观。但仅自1990年代起，观测者才开始有规律地记录并研究月表的光闪，可能来自小行星的撞击。1月21日月全食期间，许多摄影师不经意间捕捉到了以暗淡的红月亮为背景的小行星撞击闪光。审视在食甚相开始前拍摄的影像时被发现，这个光闪（见内插图）出现在月亮变暗的西部边缘附近。基于西班牙南部的月亮撞击探测和分析系统（MIDAS）望远镜记录到的光闪持续时间的估计，表明撞击天体的质量约为10公斤，产生了一个直径在7米到10米之间的陨石坑。