2025年10月19日
丘留莫夫-葛拉西门科Churyumov-Gerasimenko彗星形成其彗尾
影像提供与版权: ESA, Rosetta, NAVCAM
说明: 彗尾从何而来？通常在彗核上并没有明显的喷流喷出位置，从而形成彗尾。2015年，欧洲空间局的罗塞塔号探测器拍摄了一张主题影像，展示了正在形成的喷流的最佳图像之一。这艘探测器从2014年到2016年环绕着67P/丘留莫夫-葛拉西门科彗星（丘-葛彗星）。这张图片展示了当丘-葛彗星接近太阳并升温时，气体和尘埃从彗星核的多个地方喷出。彗星有两个显著的叶状结构，较大的叶状结构约有4公里宽，而较小的叶状结构则有2.5公里宽，两者由一个狭窄的颈部相连。分析显示，蒸发必须在彗星表面深处进行，才能形成我们看到的气体、尘埃和冰的喷流，这些喷流从表面喷出。丘-葛彗星（也称为67P彗星）在每6.44年的太阳公转轨道中，会因喷流而损失约一米的表面深度，这样的速度将在仅仅数千年内彻底毁灭彗星。2016年，罗塞塔号的任务结束，并以受控的方式撞击丘-葛彗星的表面。
明日的图片: big heart
Due to the lapse in federal government funding, NASA is not updating APOD website. We sincerely regret this inconvenience.
由于美国联邦政府资金中断，NASA目前暂停更新APOD网站。对此带来的不便，我们深感抱歉。
英文原文:
Explanation: Where do comet tails come from? There are usually no obvious places on the nuclei of comets from which the jets that create comet tails emanate. One of the best images of emerging jets is shown in the featured picture , taken in 2015 by ESA’s robotic Rosetta spacecraft that orbited Comet 67P/Churyumov-Gerasimenko (Comet CG) from 2014 to 2016. The picture shows plumes of gas and dust escaping numerous places from Comet CG ‘s nucleus as it neared the Sun and heated up. The comet has two prominent lobes, the larger one spanning about 4 kilometers, and a smaller 2.5-kilometer lobe connected by a narrow neck. Analyses indicate that evaporation must be taking place well inside the comet’s surface to create the jets of gas, dust, and ice that we see emitted through the surface. Comet CG (also known as Comet 67P) loses in jets about a meter of surface depth during each of its 6.44-year orbits around the Sun, a rate at which will completely destroy the comet in only thousands of years. In 2016, Rosetta ‘s mission ended with a controlled impact onto Comet CG’s surface.
