2023年07月02日:南极洲上空的银河和极光-（Milky Way and Aurora over Antarctica） 2023年07月02日:南极洲上空的银河和极光-（Milky Way and Aurora over Antarctica）--原图下载{mtitle title="南极洲上空的银河和极光"/}Image Credit & Copyright: LI Hang说明: 它是那个漫漫长夜较出采的天空景观之一。在该时的南极洲某些地区，不但时值寒冬，太阳更是连续数星期都未曾冒头。然而在中国的南极中山站，人们有时会顶着酷寒出门拍摄精采的夜空。这幅主题影像，即是在2015年7月中旬南极夜行将结束时，某次冒险出门之所得。当时上指的广角镜头，不但记录了下方的地面，更捕捉到影像顶端另一侧地面的景观。影像的前景有正在拍照的同事，远处有球形的卫星接收器和数座风车 。而夜空则散布着点点繁星，其中包括天狼星和老人星。在远方的背景里，从地平线伸展到另一侧地平线的，是我们银河系的中央盘面。而在头顶附近的更遥远后方，可见到以弥漫光斑之姿现身的大与小麦哲伦星系，这二个邻近我们庞大银河系的伴星系。{lamp/}原文：{mtitle title="Milky Way and Aurora over Antarctica"/}Image Credit & Copyright: LI HangExplanation: It was one of the better skies of this long night.In parts of Antarctica, not only is it winter, but the Sun can spend weeks below the horizon.At China's Zhongshan Station, people sometimes venture out into the cold to photograph a spectacular night sky.The featured image from one such outing was taken in mid-July of 2015, just before the end of this polar night.Pointing up, the wide angle lens captured not only the ground at the bottom, but at the top as well. In the foreground, a colleague is taking pictures.In the distance, a spherical satellite receiver and several windmills are visible.Numerous stars dot the night sky, including Sirius and Canopus.Far in the background, stretching overhead from horizon to horizon, is the central band of our Milky Way Galaxy.Even further in the distance, visible as extended smudges near the top, are the Large and Small Magellanic Clouds, satellite galaxies near our huge Milky Way Galaxy.

2023年05月31日:模拟：盘状星系的形成-（Simulation: A Disk Galaxy Forms） 2023年05月31日:模拟：盘状星系的形成-（Simulation: A Disk Galaxy Forms）--原图下载2023 May 31 {mtitle title="模拟：盘状星系的形成"/}Video Credit: TNG Collaboration, MPCDF, FAS Harvard U.;Music: World's Sunrise (YouTube: Jimena Contreras)说明: 我们从何而来的？我们生活在一个绕行恒星、然后再一同绕星系运行的行星上，但这一切到底是如何形成的？由于我们宇宙的变动过于缓慢而难以追蹤，只能借助于快速的电脑模拟来找出答案。具体来说，这部来自IllustrisTNG合作团队的主题影片，追蹤了气体从早期宇宙（红移12）到如今（红移0）如何移动。在模拟启始之时，周边的气体坠入并聚集在重力相对高的区域里。数十亿年之后，一个明确的核心从一场奇幻而迷人的宇宙之舞中形成出来。气团里的部分斑点为小型伴星系，它们在我们这个年代降临、影片结束时，掉入旋转的星系里并被吸收。然而对银河系来说，大型合併可能还没结束，因为最近的证据显示，我们的大螺旋盘状星系将在接下来的数十亿年内，与更大的仙女螺旋盘状星系互撞并合併。{lamp/}原文：{mtitle title="Simulation: A Disk Galaxy Forms"/}Video Credit: TNG Collaboration, MPCDF, FAS Harvard U.;Music: World's Sunrise (YouTube: Jimena Contreras)Explanation: How did we get here?We know that we live on a planet orbiting a star orbiting a galaxy, but how did all of this form?Since our universe moves too slowly to watch, faster-moving computer simulations are created to help find out.Specifically, this featured video from the IllustrisTNG collaborationtracks gas from the early universe (redshift 12) until today (redshift 0).As the simulation begins, ambient gas falls into and accumulates in a region of relatively high gravity. After a few billion years, a well-defined center materializes from a strange and fascinating cosmic dance.Gas blobs -- some representing small satellite galaxies -- continue to fall into and become absorbed by the rotating galaxy as the present epoch is reached and the video ends. For the Milky Way Galaxy, however, big mergers may not be over -- recent evidence indicates that our large spiral disk Galaxy will collide and coalesce with the slightly larger Andromeda spiral disk galaxy in the next few billion years.

2023年05月29日:蓝绿色仙境上空的银河-（Milky Way over a Turquoise Wonderland） [2023年05月29日:蓝绿色仙境上空的银河-（Milky Way over a Turquoise Wonderland）--原图下载](https://apod.nasa.gov/apod/image/2305/SeaBlueSky_Horalek_960.jpg"onMouseOver="if (document.images)document.imagename1.src='image/2305/SeaBlueSky_Horalek_960_annotated.jpg';"onMouseOut="if (document.images)document.imagename1.src='image/2305/SeaBlueSky_Horalek_960.jpg';){mtitle title="蓝绿色仙境上空的银河"/}Image Credit & Copyright: Petr Horálek /Institute of Physics in Opava,Sovena Jani说明: 那里有什么在发光？答案取决于提问是指海还是天？在海中，不寻常的蓝色辉光是来自生物发光（译注：俗称蓝眼泪）。具体来说，微弱的光来自夜光虫，亦即受到激荡海浪激发的单细胞浮游生物。浮游生物则利用它们的辉光来惊吓和照亮捕食者。于今年的2月中旬，蓝眼泪在马尔地夫的一座小屿附近格外活跃，因此这位天文摄影者称之为蓝绿色的仙境。而作为对比，当时的天空更是充满很熟悉的恒星和星云之辉光。从人为照亮的绿色植物后方升起的泛白光带，是由数十亿颗恒星聚成的银河系中央盘面。此外，在天空中还可见到左侧的半人马座欧米茄星团，以及中间着名的南十字 星官。影像中的泛红星云，则有中右侧的明亮船底大星云及右上角的广袤甘姆星云。{lamp/}原文：{mtitle title="Milky Way over a Turquoise Wonderland"/}Image Credit & Copyright: Petr Horálek /Institute of Physics in Opava,Sovena JaniExplanation: What glows there? The answer depends: sea or sky?In the sea, the unusual blue glow is bioluminescence.Specifically, the glimmer arises from Noctiluca scintillans, single-celled plankton stimulated by the lapping waves.The plankton use their glow to startle and illuminate predators. This mid-February display on an island in the Maldives was so intense that the astrophotographer described it as a turquoise wonderland.In the sky, by contrast, are the more familiar glows of stars and nebulas.The white band rising from the artificially-illuminated green plants is created by billions of stars in the central disk of our Milky Way Galaxy. Also visible in the sky is the star cluster Omega Centauri, toward the left, and the famous Southern Cross asterism in the center.Red-glowing nebulas include the bright Carina Nebula, just right of center, and the expansive Gum Nebula on the upper right.

2023年05月19日:螺旋星系M63-（Curly Spiral Galaxy M63） 2023年05月19日:螺旋星系M63-（Curly Spiral Galaxy M63）--原图下载{mtitle title="螺旋星系M63"/}Image Credit &Copyright: Sophie Paulin,Jens Unger,Jakob Sahner版权: 位在猎犬座方向，离我们约3千万光年远的M63，是北半球天空的明亮螺旋星系之一。这个编录号为NGC 5055、跨幅将近100,000光年的壮丽宇宙岛，几乎和我们的银河系等大。在这幅极深空的影像里，除了可见到为它博得向日葵星系称号的明亮的核心及宏伟的螺旋臂之外，还可见到向外晕伸展的暗淡弧形恒星流。这些伸展到离星系核心约180,000光年远的结构，可能是M63以潮汐力撕碎其伴星系之后，所遗留下来的恒星流。在这幅极宽视野的影像里，还可见到M63的其他伴星系及昏暗的矮星系，在接下来的数十亿年之中，它们可能也会化身为恒星流。{lamp/}原文：{mtitle title="Curly Spiral Galaxy M63"/}Image Credit &Copyright: Sophie Paulin,Jens Unger,Jakob SahnerExplanation: A bright spiral galaxy of the northern sky,Messier 63is nearby,about 30 million light-years distant toward the loyal constellationCanes Venatici.Also cataloged as NGC 5055, the majesticisland universeis nearly 100,000 light-years across, about the sizeof our own Milky Way.Its bright coreand majesticspiral arms lend the galaxyits popular name, The Sunflower Galaxy.This exceptionally deep exposure also followsfaint, arcing star streams far into the galaxy'shalo.Extending nearly 180,000 light-years from the galactic center, the star streams are likely remnants oftidally disruptedsatellites of M63.Other satellite galaxies of M63 can be spotted inthe remarkable wide-field image,including faintdwarf galaxies,which could contribute to M63's star streams in the next few billionyears.

2023年03月30日:NGC 4372与暗带星云-（NGC 4372 and the Dark Doodad） 2023年03月30日:NGC 4372与暗带星云-（NGC 4372 and the Dark Doodad）--原图下载{mtitle title="NGC 4372与暗带星云"/}Image Credit &Copyright:Matias Tomasello说明: 在南天飘流的悦目暗[饰]带星云，是苍蝇座内用双筒望远镜观星的吸睛标的。这团以富星场为衬托的宇宙尘埃云，位在煤袋星云及南十字星群之南。在这片望远镜视野里绵延了将近3度的暗带星云，其南端看似终止于右上方的泛黄球状星云NGC 4372。不过，于银河系银晕里漫游的NGC 4372，是远在20,000多光年之外的背景天体，只是凑巧和暗带星云在同一视线方向。拥有鲜明边界的暗带星云，是苍蝇分子云的一部份，它贴切的暱称，是由天文摄影者／作家Dennis di Cicco 1986年在澳洲荒野观测哈雷彗星时所提出的。暗带星云离我们约700光年远，长度则超过30光年。 （Dark Doodad Nebula 暗[饰]带星云）{lamp/}原文：{mtitle title="NGC 4372 and the Dark Doodad"/}Image Credit &Copyright:Matias TomaselloExplanation: The delightful Dark Doodad Nebula driftsthrough southern skies,a tantalizing target for binoculars toward the small constellationMusca, The Fly.The dusty cosmic cloudis seen against rich starfields just south of theCoalsack Nebula and the Southern Cross.Stretching for about 3 degrees across the center of this telephoto field of view, the Dark Doodadis punctuated near its southern tip (upper right) by yellowishglobular star clusterNGC 4372.Of course NGC 4372 roams the halo ofour Milky Way Galaxy,a background object some 20,000 light-years away and onlyby chance along our line-of-sight to the Dark Doodad.The Dark Doodad's well defined silhouette belongs to theMusca molecularcloud, but its better known alliterative moniker was firstcoined byastro-imager and writerDennis di Cicco in 1986 whileobserving Comet Halley from the Australian outback.The Dark Doodad is around 700 light-years distantand over 30 light-years long.

2023年03月22日:M31：仙女大星系-（M31: The Andromeda Galaxy） 2023年03月22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 & Copyright: Abdullah Al-Harbi说明: 你能看多远？ 人类肉眼能轻易见到的最远天体是M31 (仙女大星系)，离我们有2百多万光年远。不过，如果没借助于望远镜，这个庞大的螺旋星系，看起来只是仙女座的一团不起眼的暗淡弥漫云气。在这幅以最邻近大星系为主题的15小时长曝光望远镜数位组合影像里，仙女大星系明亮的泛白核心、蜿蜒黝黑的尘埃带、明亮的泛蓝螺旋臂、与泛红的发射星云皆历历在目。不过，我们怎么知道这团”螺旋星云“真的有这么远？此提问是着名的1920年Shapley-Curtis大辩论之中心议题。后来在1920年代，经由观测能分辨、带有规律亮度变化的恒星，找出了它们的真实距离，从而测定了M31的距离。所得到的结果证实M31是个位阶与我们银河系相当的天体，而这个结论， 也让宇宙的规模远远超出先前所想的。{lamp/}原文：{mtitle title="M31: The Andromeda Galaxy"/}Image Credit & Copyright: Abdullah Al-HarbiExplanation: How far can you see?The most distant object easily visible to the unaided eye is M31, the great Andromeda Galaxy, over two million light-years away. Without a telescope, even this immense spiral galaxy appears as an unremarkable, faint, nebulous cloud in the constellation Andromeda. But a bright white nucleus, dark winding dust lanes, luminous blue spiral arms, and bright red emission nebulas are recorded in this stunning fifteen-hour telescopic digital mosaic of our closest major galactic neighbor. But how do we know this spiral nebula is really so far away?This question was central to the famous Shapley-Curtis debate of 1920. M31's great distance was determined in the 1920s by observations that resolved individual stars that changed their brightness in a way that gave up their true distance.The result proved that Andromeda is just like our Milky Way Galaxy -- a conclusion making the rest of the universe much more vast than had ever been previously imagined.