2025年1月28日
Comet G3 ATLAS over Uruguay
Image Credit & Copyright: Mauricio Salazar
Explanation: Comets can be huge. When far from the Sun, a comet’s size usually refers to its hard nucleus of ice and rock, which typically spans a few kilometers — smaller than even a small moon. When nearing the Sun, however, this nucleus can eject dust and gas and leave a thin tail that can spread to an enormous length — even greater than the distance between the Earth and the Sun. Pictured, C/2024 G3 (ATLAS) sports a tail of sunlight-reflecting dust and glowing gas that spans several times the apparent size of a full moon, appearing even larger on long duration camera images than to the unaided eye. The featured image shows impressive Comet ATLAS over trees and a grass field in Sierras de Mahoma, San Jose, Uruguay about a week ago. After being prominent in the sunset skies of Earth’s southern hemisphere, Comet G3 ATLAS is now fading as it moves away from the Sun, making its impressive tails increasingly hard to see.
Gallery: Comet ATLAS (G3)
Tomorrow’s picture: star circles
乌拉圭上空的阿特拉斯彗星
影像提供与版权: Mauricio Salazar
说明: 彗星可以是庞然大物。在离太阳很远时，彗星的大小是指由冰和岩石构成的坚实彗核，其宽度通常仅有数公里，甚至比小卫星还要娇小。不过，当来到太阳附近时，彗核会释出尘埃和气体，形成细长的彗尾，而彗尾可能极长，其长度甚至可超过地球与太阳的间距。如这幅影像所示，阿特拉斯彗星（C/2024 G3 ATLAS）曳着大把反射阳光的尘埃及发光气体长尾，而其跨幅为满月视大小的数倍之多。在长曝光的相机影像里，彗星的彗尾之规模远胜于肉眼所见。这张大约一周前摄于乌拉圭 圣何塞市马霍马山脉的主题影像，呈现了阿特拉斯彗星悬在绿树和青草地上空的壮丽景象。在地球南半球的日落后天空中，阿特拉斯彗星曾经非常吸睛，但随着它逐渐远离太阳，其亮度也在减弱，让它壮观的彗尾愈来愈难以再现。
图库: 阿特拉斯彗星
明日的图片: star circles
