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.

2023年10月14日:日晕环-（Circular Sun Halo） 2023年10月14日:日晕环-（Circular Sun Halo）--原图下载{mtitle title="日晕环"/}Image Credit &Copyright:Vincenzo Mirabella说明: 想看环拱太阳的晕环吗？在世界各地的白昼天空中，它是轻易可见的景观。张角22度、远比彩虹还常见的日晕环，是由薄薄高卷云内随机排列的冰晶所造成的。上面这幅来自手机相机的日晕影像，则是在2021年5月29日摄于义大利的罗马附近。要让明亮的晕环显现，其实只要仔细遮住日盘即可，例如这幅影像里的指尖。晕环的特徵半径，大约与手伸长时，拇指到小指头的手掌张角相当。想看火之环日食吗？这稍难一些。在今天（10月14日）的日食里，名为火之环的精采环食阶段，只有位在通过北美洲、中美洲、及南美洲的狭窄月影带内的住民才得见。不过在更辽阔的美洲区域，可见到日偏食。{lamp/}原文：{mtitle title="Circular Sun Halo"/}Image Credit &Copyright:Vincenzo MirabellaExplanation: Want to see a ring around the Sun?It's easy to doin daytime skies around the world.Created by randomly oriented ice crystals in thin high cirrus clouds,circular 22 degree halos are visible much more often than rainbows.This one wascaptured by smart phonephotographyon May 29, 2021 near Rome, Italy.Carefullyblocking the Sun,for example with a finger tip,is usually all that it takes to reveal the common bright halo ring.The halo's characteristic angular radius is about equalto the span of your hand, thumb to little finger,at the end of your outstretched arm. Want to see aring of fire eclipse?That's harder.The spectacular annular phase oftoday's (October 14) solar eclipse,known as a ring of fire,is briefly visible only when standing alongthe Moon's narrow shadow track that passes over limited parts ofNorth, Central, and South America.The solar eclipse is partial though, when seenfrom broader regions throughout the Americas.

2023年06月10日:火星与蜂巢星团-（Mars and the Beehive） 2023年06月10日:火星与蜂巢星团-（Mars and the Beehive）--原图下载{mtitle title="火星与蜂巢星团"/}Image Credit &Copyright:Rolando Ligustri说明: 在这个月日落后的西方天空中，明亮的火星及灿烂的金星是其中最醒目的天体。摄于6月3日晚上的这幅影像里，在巨蟹座里漫游的火星正好来到疏散星团M44的群星附近。亘古以来即为人们所知的这个邻近裸眼星团，亦名为鬼宿星团（Praesepe）或蜂巢星团。距离我们只有600光年远的蜂巢星团，其成员星皆远比太阳年轻。而带着淡黄晕光的火星，则大约距离我们17光分。在6月12/13日那晚，金星将接续来到蜂巢星团的群星之旁。不过，金星耀眼的光芒会让蜂巢星团很难用肉眼直接观赏。{lamp/}原文：{mtitle title="Mars and the Beehive"/}Image Credit &Copyright:Rolando LigustriExplanation: This month, bright Mars and brilliant Venusare the prominent celestial beacons inplanet Earth's western skies after sunset.Wandering through the constellation Cancer the Crab, the Red Planet wascaptured hereon the evening of June 3 near the stars ofopen cluster Messier 44.Recognized since antiquity this nearby, naked-eye star cluster is also knownas the Praesepe or the Beehive cluster.A swarm of stars all much younger than the Sun, the Beehive cluster isa mere 600 light-years distant.Seen with a yellowish hue, Mars is about 17 light-minutes away.On June 12/13 Venuswill take its turn posing next to the stars ofthe Beehive cluster.But the dazzling light of Venus will make the Beehive starsdifficult to see by eye alone.

2023年04月30日:土卫十二的彩色影像-（Saturn's Moon Helene in Color） 2023年04月30日:土卫十二的彩色影像-（Saturn's Moon Helene in Color）--原图下载{mtitle title="土卫十二的彩色影像"/}Image Credit: NASA, JPL-Caltech, SSI;Processing: Daniel Macháček说明: 儘管其颜色或许很平淡，但土卫十二（Helene）不管怎么看都是个谜样的天体。在2012年，当时绕行土星的卡西尼号太空船，俯冲到离这颗娇小卫星不到1个地球直径的距离，并为它拍下了一批上面这种前所未见的细緻影像。而在上面这幅影像里，除了可见到寻常的撞击坑和山丘之外，更记录了看起来异常平滑的带纹原野。行星天文学家正在检视土卫十二的这些细緻影像，一点一滴的收集攸关这座30公里宽漂浮冰山的起源和演变之线索。土卫十二的其他不寻常之处，还有它绕行土星的轨道位置，正好在大卫星土卫四（Dione）的前方，这使它成为现知的4颗、位于名为稳定拉格朗日点（重力井）里的土星卫星之一。{lamp/}原文：{mtitle title="Saturn's Moon Helene in Color"/}Image Credit: NASA, JPL-Caltech, SSI;Processing: Daniel MacháčekExplanation: Although its colors may be subtle, Saturn's moon Helene is an enigma in any light.The moon was imaged in unprecedented detail in 2012 as the robotic Cassini spacecraft orbiting Saturn swooped to within a single Earth diameter of the diminutive moon.Although conventional craters and hills appear, the aboveimage also shows terrain that appears unusually smooth and streaked.Planetary astronomers are inspecting these detailed images of Helene to glean clues about the origin and evolution of the 30-km across floating iceberg.Helene is also unusual because it circles Saturn just ahead of the large moon Dione, making it one of only four known Saturnian moons to occupy a gravitational dimple known as a stable Lagrange point.

2023年03月29日:SH2-308：海豚状的恆星气泡-（Sh2-308: A Dolphin Shaped Star Bubble） 2023年03月29日:SH2-308：海豚状的恆星气泡-（Sh2-308: A Dolphin Shaped Star Bubble）--原图下载{mtitle title="SH2-308：海豚状的恆星气泡"/}Image Credit & Copyright: Aleix Roig (AstroCatInfo)说明: 是那颗恒星产生了这团气泡？并不是气泡右侧的亮星。同时它也不是一头庞大的太空海豚。造就这个气泡的恒星，是位在这团泛蓝星云中心的活跃沃夫-瑞叶型恒星。沃夫-瑞叶型恒星的质量通常是太阳的20倍以上，能发出高速粒子风形成这类形状具有特徵性的星云。在此案例里，所产生的星云宽度超过60光年，年龄约为70,000年，而形状恰好很像海豚的头部。 这个编录号为Sh2-308、暱称为海豚头星云的团状云气，距离我们约5,000光年远，在天空的张角和满月相当，只是亮度远为暗淡。 在这幅主题影像左侧的泛红云气，其形状及之所会发光，可能也是受到这颗沃夫-瑞叶型恒星辐射的高能星光之塑形及激发。{lamp/}原文：{mtitle title="Sh2-308: A Dolphin Shaped Star Bubble"/}Image Credit & Copyright: Aleix Roig (AstroCatInfo)Explanation: Which star created this bubble?It wasn't the bright star on the bubble's right.And it also wasn't a giant space dolphin.It was the star in the blue nebula's center, a famously energetic Wolf-Rayet star.Wolf-Rayet stars in general have over 20 times the mass of our Sun and expel fast particle winds that can create iconic looking nebulas.In this case, the resulting star bubble spans over 60 light years, is about 70,000 years old, and happens to look like the head of a dolphin. Named Sh2-308 and dubbed the Dolphin-Head Nebula, the gas ball lies about 5,000 light years away and covers as much sky as the full moon -- although it is much dimmer.The nearby red-tinged clouds on the left of the featured image may owe their glow and shape to energetic light emitted from the same Wolf-Rayet star.

2023年02月07日:彗星与大、小北斗-（A Comet and Two Dippers） [2023年02月07日:彗星与大、小北斗-（A Comet and Two Dippers）--原图下载](https://apod.nasa.gov/apod/image/2302/ZtfDippersB_Horalek_960_annotated.jpg"onMouseOver="if (document.images)document.imagename1.src='image/2302/ZtfDippersB_Horalek_960.jpg';"onMouseOut="if (document.images)document.imagename1.src='image/2302/ZtfDippersB_Horalek_960_annotated.jpg';){mtitle title="彗星与大、小北斗"/}Image Credit & Copyright: Petr Horalek /Institute of Physics in Opava说明: 你还能看到ZTF彗星吗？是的。纵然彗星C/2022 E3（ZTF）逐渐变暗，但如果在这段期间你知道该在何时往何处看，仍有机会看到它。几何上来说，ZTF彗星已经通过最靠近太阳及地球的位置，目前正往太阳系外围远去。在上个月通过北极星及大北斗与小北斗附近之后，在它绕行太阳的轨道上，于接下来的整个月都会在北天飞掠。如上面这幅影像所示，在1月底拍照之时，ZTF彗星曳着伸展长度超过10度的离子尾，刚好通过大北斗与小北斗之间。目前ZTF彗星的亮度已在裸视极限以下，不过仍然可以靠双筒或小望远远镜及一幅好星图找到它。在下星期，观赏这颗彗星的好时机是在太阳下山之后，但在月亮升起之前。在接下来的这几天里，ZTF彗星将移到火星前方附近。{lamp/}原文：{mtitle title="A Comet and Two Dippers"/}Image Credit & Copyright: Petr Horalek /Institute of Physics in OpavaExplanation: Can you still see the comet? Yes. Even as C/2022 E3 (ZTF) fades, there is still time to see it if you know where and when to look.Geometrically, Comet ZTF has passed its closest to both the Sun and the Earth and is now headed back to the outer Solar System.Its orbit around the Sun has it gliding across the northern sky all month, after passing near Polaris and both the Big and Little Dippers last month.Pictured, Comet ZTF was photographed between the two dippers in late January while sporting an ion tail that extended over 10 degrees.Now below naked-eye visibility, Comet ZTF can be found with binoculars or a small telescope and a good sky map. A good time to see the comet over the next week is after the Sun sets -- but before the Moon rises.The comet will move nearly in front of Mars in a few days