2024年09月09日:火星的卫星、撞击坑与火山-（Mars: Moon, Craters, and Volcanos） 2024年09月09日:火星的卫星、撞击坑与火山-（Mars: Moon, Craters, and Volcanos）--原图下载{mtitle title="火星的卫星、撞击坑与火山"/}Image Credit: ESA, DLR, FU Berlin, Mars Express;Processing & CC BY 2.0 License:Andrea Luck; h/t: Phil Plait说明: 如果你能飞越火星，可能会看到什么？这幅由火星特快车号摄于今年7月、俯视火星上一块特别有趣区域的主题影像，正是此提问的答卷。影像的右上方，可见到火星最着名的景点奥林帕斯山，它同时也是太阳系中最大的火山。影像右侧的地平线上，可见另一座火星大火山帕弗尼斯山。在这颗名副其实的红色行星表面，还可见到几个圆形的撞击坑。而这张影像拍摄的时间，也抓得非常精准，刚好记录到出现在中左方黝黑、注定灭亡的火卫一。左下方的表面特徵称为欧克斯凹口（Orcus Patera），因其大小及长椭圆形状而着称，同时它也很神秘，因为其形成它的过程至今仍不明。欧洲航天局的火星特快车号太空船于2003年发射升空，除了完成了许多重要的科学发现之外，它也为火星曾有大水体提供了支持的证据。{lamp/}原文：{mtitle title="Mars: Moon, Craters, and Volcanos"/}Image Credit: ESA, DLR, FU Berlin, Mars Express;Processing & CC BY 2.0 License:Andrea Luck; h/t: Phil PlaitExplanation: If you could fly over Mars, what might you see?The featured image shows exactly this in the form of a Mars Express vista captured over a particularly interesting region on Mars in July.The picture's most famous feature is Olympus Mons, the largest volcano in the Solar System, visible on the upper right. Another large Martian volcano is visible on the right horizon: Pavonis Mons.Several circular impact craters can be seen on the surface of the aptly named red planet.Impressively, this image was timed to capture the dark and doomed Martian moon Phobos, visible just left of center. The surface feature on the lower left, known as Orcus Patera, is unusual for its large size and oblong shape, and mysterious because the processes that created it still remain unknown. ESA's robotic Mars Express spacecraft was launched in 2003 and, among many notable science discoveries, bolstered evidence that Mars was once home to large bodies of water.

2024年09月08日:M31：仙女大星系-（M31: The Andromeda Galaxy） 2024年09月08日:M31：仙女大星系-（M31: The Andromeda Galaxy）--原图下载{mtitle title="M31：仙女大星系"/}Image Credit: Subaru (NAOJ), Hubble(NASA/

2024年09月07日:火卫二：娇小的火星卫星-（Small Moon Deimos） 2024年09月07日:火卫二：娇小的火星卫星-（Small Moon Deimos）--原图下载{mtitle title="火卫二：娇小的火星卫星"/}Image Credit: HiRISE, MRO, LPL (U. Arizona), NASA说明: 火星有2颗娇小的卫星，它们分别是以希腊神话人物“恐惧"和"恐慌"为名的火卫一（Phobos）与火卫二（Deimos）。上面这2个图板，呈现了较小的卫星火卫二的细緻表面景观。这些影像，是由美国航太总署长期监测火星的火星勘测轨道船上的HiRISE相机摄于2009年。宽约15公里火卫二，是2颗火星卫星中最外侧的那颗，也是太阳系已知的卫星中最小的一个。这2颗火星卫星，都是由在美国华盛顿海军观测站工作的天文学家霍耳发现于1877年，但它们的存在的假设，则是由发现行星运动定律的天文学家开普勒在1610年左右提出的。开普勒的假设并无科学根据，但他的着作和想法却影响深远，以至于约翰逊‧斯威夫特所写的《格列佛游记》，就曾讨论这2颗火星卫星。这本小说写于1726年，比这2颗卫星真正的发现要超前150多年。{lamp/}原文：{mtitle title="Small Moon Deimos"/}Image Credit: HiRISE, MRO, LPL (U. Arizona), NASAExplanation: Mars has two tiny moons, Phobos and Deimos,named for the figures in Greek mythology Fear and Panic.Detailed surface views of smaller moon Deimos are shownin both these panels.Theimages were taken in 2009,by the HiRISE camera on board the Mars Reconnaissance Orbiterspacecraft, NASA's long-livedinterplanetary internetsatellite.The outermost of the two Martian moons,Deimos is one of the smallest known moons in the Solar System, measuring only about 15 kilometers across. Both Martian moons were discovered in 1877 by Asaph Hall, an American astronomer working at the US Naval Observatory in Washington D.C.But their existence was postulated around 1610 by Johannes Kepler, the astronomer who derived the laws of planetary motion.In this case, Kepler's predictionwas not based on scientific principles, buthis writings and ideas were so influential that the two Martian moonsare discussed in works of fiction such as Jonathan Swift's Gulliver's Travels, written in 1726, over 150 years before their discovery.

2024年09月06日:海王星：带环冰质巨行星-（Ringed Ice Giant Neptune） 2024年09月06日:海王星：带环冰质巨行星-（Ringed Ice Giant Neptune）--原图下载{mtitle title="海王星：带环冰质巨行星"/}Image Credit: NASA,ESA,CSA,STScI,NIRCam说明: 在这幅由韦伯太空望远镜所拍摄的清晰近红外光影像里，带环冰质巨行星─海王星位于影像的中心附近。这颗昏暗的天体是离太阳最遥远的行星，与太阳的距离大约为地球的30倍。而在这幅令人讚叹的韦伯影像里，这颗行星之所以会有黝黑幽灵般的外观，则是因为它大气中的甲烷吸收红外光所致。此外，在这幅影像里，伸展到海王星高吸收甲烷上方的高层云清楚可辨。影像中，位在左上方、包裹着氮冰、比海王星要明亮的海王星最大卫星海卫一，周围带着韦伯望远镜特徵性的衍射芒。在这片视野里，包括海卫一在内共可辨认出海王星14颗已知卫星中的7颗。在这张摄于太空的行星新影像里，海王星暗淡的行星环格外引人注目。自1989年8月航行者2号太空船造访海王星以来，这是首次再见到了海王星複杂环系的细节。{lamp/}原文：{mtitle title="Ringed Ice Giant Neptune"/}Image Credit: NASA,ESA,CSA,STScI,NIRCamExplanation: Ringed ice giant Neptunelies near the center of this sharpnear-infrared image from theJames Webb Space Telescope.The dim and distant world is thefarthest planet from the Sun,about 30 times farther away than planet Earth.But in the stunning Webb view, the planet's dark and ghostly appearanceis due to atmospheric methane that absorbs infrared light.High altitude clouds that reach above most of Neptune's absorbing methaneeasily stand out in the image though.Coated with frozen nitrogen, Neptune's largest moon Triton isbrighter than Neptune in reflected sunlight,seen at the upper left sporting the Webb telescope's characteristicdiffraction spikes.Including Triton, seven of Neptune's 14 known moons can beidentifiedin the field of view.Neptune's faint ringsare striking in this space-basedplanetary portrait.Details of the complex ring system are seen here for the firsttime since Neptune was visited by theVoyager 2 spacecraft in August 1989.

2024年09月05日:NGC 247及附近的天体-（NGC 247 and Friends） 2024年09月05日:NGC 247及附近的天体-（NGC 247 and Friends）--原图下载{mtitle title="NGC 247及附近的天体"/}Image Credit &Copyright: Acquisition -Eric Benson,Processing -DietmarHager说明: 宽约70,000光年的NGC 247，是一个比我们银河系小的螺旋星系。它的距离只有1千1百万光年远，因此是银河系的近邻。从我们的视点看出去，几乎是侧向的这个星系，是这幅远眺南天鲸鱼座的望远镜影像里最庞大的天体。而这个星系盘面上的鲜明缺口，更为它博得针眼星系的雅号。在这幅清晰的星系影像里，还可看到许多背景星系，包括NGC 247左下方，距离在3亿光年左右，名为柏比奇鍊的4个成串星系。NGC 247和明亮的螺旋星系NGC 253，皆是玉夫座星系群的成员。{lamp/}原文：{mtitle title="NGC 247 and Friends"/}Image Credit &Copyright: Acquisition -Eric Benson,Processing -DietmarHagerExplanation: About 70,000 light-years across,NGC 247is a spiral galaxy smaller than our Milky Way.Measured to beonly 11 million light-years distant it is nearby though.Tilted nearly edge-on as seenfrom our perspective,it dominates this telescopic field of view toward thesouthern constellation Cetus.The pronounced void on one side of the galaxy's disk recallsfor some its popular name, the Needle's Eye galaxy.Many background galaxies are visible inthis sharp galaxy portrait,including the remarkable string of four galaxiesjust below and left of NGC 247 known as Burbidge's Chain.Burbidge's Chain galaxiesare about 300 million light-years distant.NGC 247 itself is part of the Sculptor Group of galaxies along withshiny spiral NGC 253.

2024年09月04日:NGC 6995：蝙蝠星云-（NGC 6995: The Bat Nebula） 2024年09月04日:NGC 6995：蝙蝠星云-（NGC 6995: The Bat Nebula）--原图下载{mtitle title="NGC 6995：蝙蝠星云"/}Image Credit & Copyright: Mike Taivalmaa说明: 你能认出蝙蝠吗？ 牠就出没在这幅东面纱星云的特写影像里。面纱星云则是个大型的超新星遗迹，是大质量恒星发生死亡爆炸时，所抛出的扩张碎片云。几近圆环状的面纱星云，涵盖天鹅座方向约3度的天空，不过编录号为NGC 6995的蝙蝠星云，跨度只有半度，和满月的视大小相当。以面纱星云离地球1,400光年的距离来换算，这幅影像涵盖此星云约12光年的区域。在这幅由窄波段滤镜影像数据组合而成的影像里，遗迹内氢原子发出的辐射以红色来呈现，而氧原子的明亮辐射线则以蓝色渐层来显示。在面纱星云的西侧，还有另一个会让人联想起万圣节的女巫帚星云。{lamp/}原文：{mtitle title="NGC 6995: The Bat Nebula"/}Image Credit & Copyright: Mike TaivalmaaExplanation: Can you see the bat? It hauntsthis cosmic close-up of the eastern Veil Nebula. The Veil Nebula itself is alarge supernova remnant, the expanding debris cloud from the death explosion of a massive star.While the Veil is roughly circular in shape and covers nearly 3 degreeson the sky toward the constellation of the Swan (Cygnus), NGC 6995, known informally as the Bat Nebula, spans only 1/2 degree, about the apparent sizeof the Moon.That translates to 12 light-years at the Veil'sestimated distance, a reassuring 1,400 light-years from planet Earth.In the composite of image data recorded through narrow band filters, emission from hydrogen atoms in the remnant is shown in red with strong emission from oxygen atoms shown in hues of blue.Of course, in the western part of the Veil lies another seasonal apparition:the Witch's Broom Nebula.