2025年02月05日:智利山丘上空西落的阿特拉斯彗星-（Comet G3 ATLAS Setting over a Chilean Hill） 2025年02月05日:智利山丘上空西落的阿特拉斯彗星-（Comet G3 ATLAS Setting over a Chilean Hill）--原图下载2025 February 5 {mtitle title="智利山丘上空西落的阿特拉斯彗星"/}Video Credit & Copyright: Gabriel Muñoz说明: 阿特拉斯彗星要前往何方？在这部缩时影片里，彗星本身只移动少许，但地球的自转让它看似落向山丘后方。这组阿特拉斯彗星（C/2024 G3 ATLAS）的序列影像，是在1月22日用普通的相机摄于智利中部的阿劳卡尼亚大区。 在过去几星期里，阿特拉斯彗星一直是地球 南半球夜空中令人讚叹的壮丽景观，其亮度与壮观的程度，有机会为它博得2025年大彗星的美誉。然而很遗憾的是，阿特拉斯彗星可能那里也去不了，因为其彗核已在上个月接近太阳时发生崩解。儘管如此，彗星散落的部分岩石与冰屑残骸，会持续绕行太阳，有些甚至沿着原先彗核远离的轨道前行。{lamp/}原文：{mtitle title="Comet G3 ATLAS Setting over a Chilean Hill"/}Video Credit & Copyright: Gabriel MuñozExplanation: Where is Comet ATLAS going?In the featured time-lapse video, the comet is not itself moving very much, but the Earth's rotation makes it appear to be setting over a hill.The Comet C/2024 G3 (ATLAS) sequence was captured with an ordinary camera on January 22 from the Araucanía Region in central Chile.Comet ATLAS has been an impressive site in the evening skies of Earth's Southern Hemisphere over the past few weeks, so bright and awe-inspiring that it may eventually become known as the Great Comet of 2025.Unfortunately, Comet G3 ATLAS is not going anywhere anymore because its central nucleus broke up during its close pass to the Sun last month.Some of the comet's scattered remains of rocks and ice will continue to orbit the Sun, some in nearly the same outward section of the orbit that the comet's nucleus would have taken.

2025年02月04日:反云隙光：西班牙上空的彩虹扇-（Anticrepuscular Rays: A Rainbow Fan over Spain） 2025年02月04日:反云隙光：西班牙上空的彩虹扇-（Anticrepuscular Rays: A Rainbow Fan over Spain）--原图下载{mtitle title="反云隙光：西班牙上空的彩虹扇"/}Image Credit & Copyright: Julene Eiguren说明: 对了，你看到的彩虹有这么精采吗？ 在那天的傍晚时分，太阳一如往常的西落，然而，此时最吸睛的，反而是与落日180度反向的东方景观。于东方的天空中，不仅看见一道美丽的彩虹，还能见到看似从彩虹中心射出的反云隙光。 在这张摄于西班牙北部勒基蒂奥镇的照片里，太阳位于摄影者身后。彩虹是阳光被雨滴反射的产物，而反云隙光是因为阳光被云层部分遮挡所产生的影子，然后在穿过天空后，看似会聚于180度反向地平线上的光学幻觉。 彩虹本身就已经够精采，反云隙光则是罕见的光学现象，而能将二者同时捕捉入镜，不仅非常难得，更成就了静谧又梦幻的奇景。{lamp/}原文：{mtitle title="Anticrepuscular Rays: A Rainbow Fan over Spain"/}Image Credit & Copyright: Julene EigurenExplanation: Yes, but can your rainbow do this?Late in the day, the Sun set as usual toward the west.However, on this day, the more interesting display was 180 degrees around -- toward the east.There, not only was a rainbow visible, but an impressive display of anticrepuscular rays from the rainbow's center.In the featured image from Lekeitio in northern Spain, the Sun is behind the camera.The rainbow resulted from sunlight reflecting back from falling rain.Anticrepuscular rays result from sunlight, blocked by some clouds, going all the way around the sky, overhead, and appearing to converge on the opposite horizon -- an optical illusion. Rainbows by themselves can be exciting to see, and anticrepuscular rays a rare treat, but capturing them both together is even more unusual -- and can look both serene and surreal.

2025年02月03日:沃夫-瑞叶恆星124:恆星风机器-（Wolf-Rayet Star 124: Stellar Wind Machine） 2025年02月03日:沃夫-瑞叶恆星124:恆星风机器-（Wolf-Rayet Star 124: Stellar Wind Machine）--原图下载{mtitle title="沃夫-瑞叶恆星124:恆星风机器"/}Image Credit: Hubble Legacy Archive,NASA,ESA; Processing & License: Judy Schmidt说明: 有些恒星爆炸的过程极为缓慢。罕见、大质量的沃夫-瑞叶型恒星，极端高温而且极端活跃，它们几乎是在望远镜的注视下缓缓崩解。因为在猛烈恒星风的吹送下，恒星会喷出一团团通常超过30倍地球质量的光亮气体。例如于上面这张影像中心的沃夫-瑞叶型恒星124（WR 124），就以此在周围产生了宽约6光年的M1-67星云。在过去2万年之中，为何这颗恒星会缓缓自我分解，其细节仍是研究的题材。WR 124位在北天的天箭 座内，离我们约有15,000光年远。沃夫-瑞叶型恒星的宿命，可能会因它有多少质量而异，不过，许多可能会以壮观的超新星或伽玛射线爆发，来终结它们的生命。{lamp/}原文：{mtitle title="Wolf-Rayet Star 124: Stellar Wind Machine"/}Image Credit: Hubble Legacy Archive,NASA,ESA; Processing & License: Judy SchmidtExplanation: Some stars explode in slow motion. Rare, massive Wolf-Rayet stars are so tumultuous and hot that they are slowly disintegrating right before our telescopes. Glowing gas globs each typically over 30 times more massive than the Earth are being expelled by violent stellar winds. Wolf-Rayet star WR 124, visible near the featured image center,is thus creating the surrounding nebula known as M1-67, which spans sixlight years across.Details of why this star has been slowly blowing itself apart over the past 20,000 years remains a topic of research. WR 124 lies 15,000 light-years away towards the constellation of the Arrow (Sagitta). The fate of any given Wolf-Rayet star likely depends on how massive it is, but many are thought to end their lives with spectacular explosions such as supernovas or gamma-ray bursts.

2025年02月02日:阿特拉斯彗星发生崩解-（Comet G3 ATLAS Disintegrates） 2025年02月02日:阿特拉斯彗星发生崩解-（Comet G3 ATLAS Disintegrates）--原图下载{mtitle title="阿特拉斯彗星发生崩解"/}Image Credit: Lionel Majzik说明: 阿特拉斯彗星发生了什么事？ 自1月中旬掠过太阳附近后，这颗彗星的彗发就变得越来越昏暗。到了1月下旬，阿特拉斯彗星（C/2024 G3 ATLAS）几乎成为了一颗无头的彗星，儘管它在地球南半球的夜空中依然曳着壮观的彗尾。 上面这幅摄于智利 里奥乌塔多镇的组合影像，呈现了阿特拉斯彗星在1月连续数晚的照片。从中可清楚看出，彗星的彗发在早期照片里的亮度（左侧），比在后期（右侧）更明亮且更紧实。 发生这种改变的主要原因，很可能是彗星由冰与岩石组成的彗核已经崩解。阿特拉斯彗星在近日点时，曾深入水星轨道之内的太阳系内围，而该处的高温环境曾摧毁了许多的彗星。儘管如此，阿特拉斯彗星零落的残骸，仍会继续绕太阳运行。{lamp/}原文：{mtitle title="Comet G3 ATLAS Disintegrates"/}Image Credit: Lionel MajzikExplanation: What's happening to Comet G3 ATLAS?After passing near the Sun in mid-January, the head of the comet has become dimmer and dimmer.By late January, Comet C/2024 G3 (ATLAS) had become a headless wonder -- even though it continued to show impressive tails after sunset in the skies of Earth's Southern Hemisphere.Pictured are images of Comet G3 ATLAS on successive January nights taken from Río Hurtado, Chile.Clearly, the comet's head is brighter and more centrally condensed on the earlier days (left) than on later days (right). A key reason is likely that the comet's nucleus of ice and rock, at the head's center, has fragmented.Comet G3 ATLAS passed well inside the orbit of planet Mercury when at its solar closest, a distance that where heat destroys many comets. Some of comet G3 ATLAS' scattering remains will continue to orbit the Sun.

2025年02月01日:瑞典上空的夜光云-（Nacreous Clouds over Sweden） 2025年02月01日:瑞典上空的夜光云-（Nacreous Clouds over Sweden）--原图下载{mtitle title="瑞典上空的夜光云"/}Image Credit &Copyright:Vojan Höfer说明: 鲜豔色彩夺目的波状虹彩云，漂流在瑞典北部的天空中。这种名为夜光云或贝母云的高层云，相当罕见。然而，这幅1月12日拍摄时，太阳已位于当地的地平线下方的影像，就记录了它们令人难以忘怀的绚丽身影。 夜光云是一种极地平流层云，其成因通常是在无云的天空中，下平流层里的水汽因异常低温而形成冰晶所致。因此，緃然太阳已然隐没在地平线下方，而高悬在约15至25公里高空的夜光云，仍然在衍射阳光。{lamp/}原文：{mtitle title="Nacreous Clouds over Sweden"/}Image Credit &Copyright:Vojan HöferExplanation: Vivid and lustrous,wafting iridescent waves of color wash across this skyscapefrom northern Sweden.Known as nacreousclouds or mother-of-pearl clouds, they are rare.But theirunforgettableappearance was captured in this snapshot onJanuary 12 with the Sun just below the local horizon.A type of polar stratospheric cloud,they form when unusually cold temperatures in the usually cloudlesslower stratosphere form ice crystals.Still sunlit at altitudes of around 15 to 25 kilometers, the cloudsdiffract the sunlight even when the Sun itself is hidden from direct view.

2025年01月31日:变光星云NGC 2261-（The Variable Nebula NGC 2261） 2025年01月31日:变光星云NGC 2261-（The Variable Nebula NGC 2261）--原图下载{mtitle title="变光星云NGC 2261"/}Image Credit &Copyright:Tommy Lease(Denver Astronomical Society)说明: 这幅清晰望远镜影像所呈现的星际尘埃与气体云，其外观在数星期之间就会有明显的变化。发现于200多年前、编录号为NGC 2261的这个扇形星云，扇头镶着亮星麒麟R（R Mon）。NGC 2261的宽度约有1光年，距离我们约2,500光年远，在上世纪初，因天文学家哈伯曾对它进行研究，故这团谜样的宇宙云有哈伯变光星云（Hubble's Variable Nebula）之称。 那么，为何哈伯星云会变光呢？NGC 2261是个尘埃反射星云，扇形的顶端为麒麟R。最可信的变光假说认为，麒麟R附近在移动的緻密不透光尘埃结，把影子投射在尘埃云上，造成我们见到的变光现象。{lamp/}原文：{mtitle title="The Variable Nebula NGC 2261"/}Image Credit &Copyright:Tommy Lease(Denver Astronomical Society)Explanation: The interstellar cloud of dust and gas captured in thissharp telescopic snapshot is seen to change its appearancenoticeably over periods as short as a few weeks.Discovered over 200 years ago and cataloged as NGC 2261,bright star R Monocerotis lies at the tip of the fan-shaped nebula.About one light-year across and 2500 light-years away,NGC 2261 was studiedearly last century by astronomer Edwin Hubble andthe mysterious cosmic cloud is now more famous asHubble's Variable Nebula.So what makes Hubble's nebula vary?NGC 2261 is composed of a dustyreflection nebula fanning out from the starR Monocerotis.The leading variability explanationholds that dense knots of obscuring dust pass close to R Mon and cast moving shadowsacross the dust clouds in the rest of Hubble's Variable Nebula.