彗星与火流星

2021年12月20日

The Comet and the Fireball
Image Credit & Copyright: Cory Poole

Explanation: This picture was supposed to feature a comet. Specifically, a series of images of the brightest comet of 2021 were being captured: Comet Leonard. But the universe had other plans. Within a fraction of a second, a meteor so bright it could be called a fireball streaked through just below the comet. And the meteor’s flash was even more green than the comet’s coma. The cause of the meteor’s green was likely magnesium evaporating from the meteor’s pebble-sized core, while the cause of the comet’s green was likely diatomic carbon recently ejected from the comet’s city-sized nucleus. The images were taken 10 days ago over the Sacramento River and Mt. Lassen in California, USA. The fireball was on the leading edge of this year’s Geminid Meteor Shower — which peaked a few days later. Comet Leonard is now fading after reaching naked-eye visibility last week — but now is moving into southern skies.

Almost Hyperspace: Random APOD Generator

Tomorrow’s picture: a solar milky way

彗星与火流星
影像提供与版权: Cory Poole

说明: 这张影像原来是以彗星为主题。更具体的说，当时正在替2021年最明亮的彗星─李奥纳德，拍摄一序列的影像。不过宇宙自有其他规划。在拍照的转瞬间，一颗称为火流星的极明亮流星，从彗星下方飞掠而过。而这颗流星泛绿的亮闪，远比彗星的彗发更鲜艳。这颗流星的泛绿色泽，可能是来自从沙粒大小的流星核蒸出的镁，而泛绿的彗发，可能是来自刚从城市大小的彗核释出的双碳分子。这幅记录美国加州沙加缅度河及拉森山上空的影像，是摄10天前。因此，这颗火流星是位在极大期于数天后的双子流星雨之前缘。李奥纳德彗星在上星期成为肉眼可见彗星之后，目前已逐渐变暗并移入南天。

几乎超空间: 随机APOD生成器

明日的图片: a solar milky way