李奥纳德彗星摇摆的彗尾

2022年1月10日

Comet Leonard’s Tail Wag
Image Credit: NASA, NRL, STEREO-A; Processing: B. Gallagher

Explanation: Why does Comet Leonard’s tail wag? The featured time-lapse video shows the ion tail of Comet C/2021 A1 (Leonard) as it changed over ten days early last month. The video was taken by NASA’s Solar Terrestrial Relations Observatory-Ahead (STEREO-A) spacecraft that co-orbits the Sun at roughly the same distance as the Earth. Each image in this 29-degree field was subtracted from following image to create frames that highlight differences. The video clearly shows Comet Leonard’s long ion tail extending, wagging, and otherwise being blown around by the solar wind — a stream of fast-moving ions that stream out from the Sun. Since the video was taken, Comet Leonard continued plunging toward the Sun, reached its closest approach to the Sun between the orbits of Mercury and Venus, survived this closest approach without breaking apart, and is now fading as heads out of our Solar System.

Tuesday over Zoom: APOD editor to present the Best APOD Space Images of 2021

Tomorrow’s picture: around orion

李奥纳德彗星摇摆的彗尾
影像提供与版权: NASA, NRL, STEREO-A; 影像处理: B. Gallagher

说明: 为何李奥纳德彗星的彗尾会摇摆不定？这部缩时主题影片，呈现彗星C/2021 A1（李奥纳德）在上个月初10天之间的变化。这部影片是由NASA的日地关系天文台─前导卫星（STEREO-A）所拍摄；此卫星和地球共轨绕太阳公转，故其与太阳的距离和地球相近。为提高反差，影片每一幅宽29度的定格，都是前后二张照片相减所得。这部影片清楚显示，李奥纳德彗星的颀长离子尾，是受到从太阳泛流出的高速离子（太阳风）之吹袭，才会持续伸长与摇摆。在拍摄这部影片之后，李奥纳德彗星继续往它于水星和金星轨道之间的近日点飞奔，在与太阳最近距接近后并未崩解，目前已踏上远离太阳系的旅程并逐渐暗去。

周二聚焦: APOD编辑将呈现2021年APOD最佳太空图片

明日的图片: around orion