2024年07月08日:系外行星大观-（Exoplanet Zoo: Other Stars） 2024年07月08日:系外行星大观-（Exoplanet Zoo: Other Stars）--原图下载{mtitle title="系外行星大观"/}Illustration Credit & Copyright: Martin Vargic, Halcyon Maps说明: 其他恒星是否也像太阳一样拥有行星？当然有。支持的证据包括：周围绕行的行星之重力所引起的微量母星晃动，以及行星通过恒星前方时所造成的微小星光减弱。到目前为止，总共已经发现了超过5,500颗系外行星，其中的数千颗，是由NASA的开普勒卫星（Kepler）和凌日系外行星巡天卫星（TESS）任务所发现的，还有100多颗，是由欧南天文台的地面HARPS仪器所侦测的。这张主题图示，呈现了部分这些系外行星可能模样的揣测。图示中央的海王星级行星之所色泽泛蓝，是由于它们可能含有会散射蓝光的大气甲烷。图示两侧的木星级行星，由于其大气可能含有少量的碳，经由散射可能让这些行星的外观呈棕色和红色。图示里还间杂着许多色泽各异的地球级石质行星。随着发现和研究更多的系外行星，人类对类地球行星的普遍性及宇宙中生命有多常见，有了更深入的了解。{lamp/}原文：{mtitle title="Exoplanet Zoo: Other Stars"/}Illustration Credit & Copyright: Martin Vargic, Halcyon MapsExplanation: Do other stars have planets like our Sun?Surely they do, and evidence includes slight star wobbles created by the gravity of orbiting exoplanets and slight star dimmings caused by orbiting planets moving in front.In all, there have now been over 5,500 exoplanets discovered, including thousands by NASA's space-based Kepler and TESS missions, and over 100 by ESO's ground-based HARPS instrument. Featured here is an illustrated guess as to what some of these exoplanets might look like.Neptune-type planets occupy the middle and are colored blue because of blue-scattering atmospheric methane they might contain.On the sides of the illustration, Jupiter-type planets are shown, colored tan and red from the scatterings of atmospheric gases that likely include small amounts of carbon. Interspersed are many Earth-type rocky planets of many colors.As more exoplanets are discovered and investigated, humanity is developing a better understanding of how common Earth-like planets are, and how common life might be in the universe.

2024年01月15日:韦伯影像：星团IC 348-（Star Cluster IC 348 from Webb） 2024年01月15日:韦伯影像：星团IC 348-（Star Cluster IC 348 from Webb）--原图下载{mtitle title="韦伯影像：星团IC 348"/}Image Credit: NASA, ESA, CSA, STScI, and K. Luhman (Penn State U.) and C. Alves de Oliveira (ESA)说明: 有时候，最难见到的恒星才最有趣。年轻的星团IC 348，照亮了周围的细丝状尘埃。在韦伯太空望远镜最近发布的这张红外光影像里，这些捲曲细丝状尘埃带着粉红的色泽。在可见光波段，这些尘埃以反射蓝光为主，因此星团周围的物质，会带着反射星云熟悉的泛蓝色调。除了明亮的恒星之外，在IC 348 里还找到数个低温天体，这些天体之所以可见，则是它们在红外光波段很明亮。假说认为这些天体可能是小质量的棕矮星。支持这种说法的证据，包括侦测到一种不明的大气化学物质，而它很可能是先前发现于土星 大气中的碳氢化合物。这些天体的质量似乎略大于已知的行星，仅是木星的数倍之多。总之，迹证显示这个年轻星团拥有值得关注的天体，特别是指质量和行星相近、自由漂浮并未绕行任何恒星的棕矮星。{lamp/}原文：{mtitle title="Star Cluster IC 348 from Webb"/}Image Credit: NASA, ESA, CSA, STScI, and K. Luhman (Penn State U.) and C. Alves de Oliveira (ESA)Explanation: Sometimes, it's the stars that are the hardest to see that are the most interesting.IC 348 is a young star cluster that illuminates surrounding filamentary dust. The stringy and winding dust appears pink in this recently released infrared image from the Webb Space Telescope.In visible light, this dust reflects mostly blue light, giving the surrounding material the familiar blue hue of a reflection nebula. Besides bright stars, several cool objects have been located in IC 348, visible because they glow brighter in infrared light. These objects are hypothesized to be low mass brown dwarfs. Evidence for this includes the detection of an unidentified atmospheric chemical, likely a hydrocarbon, seen previously in the atmosphere of Saturn.These objects appear to have masses slightly greater than known planets, only a few times greater than Jupiter. Together, these indicate that this young star cluster contains something noteworthy -- young planet-mass brown dwarfs that float free, not orbiting any other star.

2023年11月28日:朱诺号影像：木卫三-（Ganymede from Juno） 2023年11月28日:朱诺号影像：木卫三-（Ganymede from Juno）--原图下载{mtitle title="朱诺号影像：木卫三"/}Image Credit & Copyright: NASA/JPL-Caltech/SwRI/MSSS;Processing & License:Kevin M. Gill;说明: 太阳系最大的卫星长什么模样？木星的卫星木卫三，个头甚至比水星及冥王星大；冰冷的表面则满是明亮的年轻撞击坑，其下叠着古老、黝黑、坑洼起伏的原野，并间杂着沟槽和山脊。沟槽地形的成因目前仍是研究的课题，主要的假说之一认为可能与冰板块的移动有关。木卫三咸信有个水量超过地球的海洋层，其中或许蕴藏着生命。与月亮类似，木卫三也是以同一面向着其中央行星─木星。这张主题影像，是由美国航太总署的朱诺号太空船，在2021年飞越这颗大卫星时所拍摄。经过这次近距离的飞越，朱诺号把绕行木星的轨道週期从53天缩短到43天。朱诺号将持续研究木星这颗巨行星的高重力、不寻常磁场及複杂的云层结构。{lamp/}原文：{mtitle title="Ganymede from Juno"/}Image Credit & Copyright: NASA/JPL-Caltech/SwRI/MSSS;Processing & License:Kevin M. Gill;Explanation: What does the largest moon in the Solar System look like? Jupiter's moon Ganymede, larger than even Mercury and Pluto, has an icy surface speckled with bright young craters overlying a mixture of older, darker, more cratered terrain laced with grooves and ridges. The cause of the grooved terrain remains a topic of research, with a leading hypothesis relating it to shifting ice plates. Ganymede is thought to have an ocean layer that contains more water than Earth -- and might contain life. Like Earth's Moon, Ganymede keeps the same face towards its central planet, in this case Jupiter. The featured image was captured in 2021 by NASA's robotic Juno spacecraft when it passed by the immense moon. The close pass reduced Juno's orbital period around Jupiter from 53 days to 43 days. Juno continues to study the giant planet's high gravity, unusual magnetic field, and complex cloud structures.

2023年11月14日:三行星伴石峰-（Three Planets Rock） [2023年11月14日:三行星伴石峰-（Three Planets Rock）--原图下载](https://apod.nasa.gov/apod/image/2311/MoonVenusJupiter_Passalacqua_960.jpg"onMouseOver="if (document.images)document.imagename1.src='image/2311/MoonVenusJupiter_Passalacqua_960_annotated.jpg';"onMouseOut="if (document.images)document.imagename1.src='image/2311/MoonVenusJupiter_Passalacqua_960.jpg';){mtitle title="三行星伴石峰"/}Image Credit & Copyright: Giovanni Passalacqua;Text: Liz Coelho (Pikes Peak)说明: 在黎明前渐褪的黑暗中，一个倾斜的天体三角看似架在西西里岛南端的石峰上。组成这个天体三角的是地球天空中最明亮的4个天体之3：木星、金星和月亮。虽然残月是一抺纤细的银白，但在地照光的照耀下，月亮大部分的月盘皆历历可辨。于2022年4月27日拍下这幅影像时，金星（中）和木星（左）相距大约3度，并即将发生近合。金星和木星的近合大约每年发生一次，可见诸日出前的东方或日落后的西方天空。这幅主题影像，摄于太阳这颗地球天空中最明亮的天体来临前大约１小时。{lamp/}原文：{mtitle title="Three Planets Rock"/}Image Credit & Copyright: Giovanni Passalacqua;Text: Liz Coelho (Pikes Peak)Explanation: In the fading darkness before dawn, a tilted triangle appeared to balance atop a rock formation off the southern tip of Sicily. Making up the points of the triangle are three of the four brightest objects visible in Earth’s sky: Jupiter, Venus and the Moon. Though a thin waning crescent, most of the moon’s disk is visible due to earthshine. Captured in this image on 2022 April 27, Venus (center) and Jupiter (left) are roughly three degrees apart -- and were headed toward a close conjunction. Conjunctions of Venus and Jupiter occur about once a year and are visible either in the east before sunrise or in the west after sunset. The featured image was taken about an hour before the arrival of the brightest object in Earth’s sky – the Sun.

2023年10月23日:朱诺太空船的木卫一影像-（Moon Io from Spacecraft Juno） 2023年10月23日:朱诺太空船的木卫一影像-（Moon Io from Spacecraft Juno）--原图下载{mtitle title="朱诺太空船的木卫一影像"/}Image Credit: NASA,JPL-Caltech,SwRI,MSSS;Processing & Copyright: Ted Stryk & Fernando García Navarro说明: 再来一幅影像！木星的木卫一表面之火山不断的喷发。为了进行探索，美国航太总署的朱诺号<a/>太空船，针对这颗异常奇特的卫星进行一系列的飞越。大小与地球的月亮相当的木卫一，由于受到木星和其他卫星的重力搓揉，其内部被加热，让它的表面满布着火山。这幅来自朱诺号的主题影像，摄于上星期以12,000公里的间距飞越这颗危险的活跃卫星之时。木卫一的表面覆盖着硫磺和冻结的二氧化硫，让它带着黄色、橙色和棕色等色泽。正如事先所期望的，朱诺号刚好在火山喷发时飞越，因此在主题影像的顶部附近，可见到爆发所产生的暗淡羽状流。研究木卫一的火山和羽状流，对人类深入了解木星複杂的卫星、环系和极光系统是如何进行交互作用有所助益。朱诺号计划在未来的数个月里，进行2次距离近10倍的木卫一飞越，其中一次在今年12月，另一次在2024年2月。{lamp/}原文：{mtitle title="Moon Io from Spacecraft Juno"/}Image Credit: NASA,JPL-Caltech,SwRI,MSSS;Processing & Copyright: Ted Stryk & Fernando García NavarroExplanation: There goes another one! Volcanoes on Jupiter's moon Io keep erupting.To investigate, NASA's robotic Juno<a/> spacecraft has begun a series of visits to this very strange moon.Io is about the size of Earth's moon, but because of gravitational flexing by Jupiter and other moons, Io's interior gets heated and its surface has become covered with volcanoes. The featured image is from last week's flyby, passing within 12,000 kilometers above the dangerously active world.The surface of Io is covered with sulfur and frozen sulfur dioxide, making it appear yellow, orange and brown.As hoped, Juno flew by just as a volcano was erupting -- with its faint plume visible near the top of the featured image. Studying Io's volcanoes and plumes helps humanity better understand how Jupiter's complex system of moons, rings, and auroras interact.Juno is scheduled to make two flybys of Io during the coming months that are almost 10 times closer: one in December and another in February 2024.

2023年10月17日:恆星PDS 70的吸积盘、行星及卫星-（PDS 70: Disk, Planets, and Moons） 2023年10月17日:恆星PDS 70的吸积盘、行星及卫星-（PDS 70: Disk, Planets, and Moons）--原图下载{mtitle title="恆星PDS 70的吸积盘、行星及卫星"/}Image Credit: ALMA (ESO/NAOJ/NRAO); M. Benisty et al.说明: 最受重视的并非这幅影像里的大吸积环。纵然环拱恒星PDS 70、会形成行星的大吸积环，在影像里非常清晰，而且本身也非常有趣。 也不是影像右侧、紧贴在大吸积盘内侧的行星，吸引了最多的讨论声量。虽然这颗编号为PDS 70c的行星，大小和质量都和木星很相近，而且刚形成不久。真正引起骚动的，是行星PDS 70c周围的弥漫斑块。那团弥漫的斑块，咸认是前所未见、正在凝聚成卫星的尘埃碟。这幅主题影像，是由位在北智利．阿塔卡玛高原沙漠，拥有66座电波望远镜天线碟的阿塔卡玛大毫米波阵列（ALMA）摄于2021年。根据ALMA的数据，天文学家推断这个正在形成卫星的系外行星碟，半径和地球轨道相近，而且未来或许会形成3颗左右、大小和月球相当的卫星，因此，（这个行星系统的）大卫星数量会和木星的4颗差不多。{lamp/}原文：{mtitle title="PDS 70: Disk, Planets, and Moons"/}Image Credit: ALMA (ESO/NAOJ/NRAO); M. Benisty et al.Explanation: It's not the big ring that's attracting the most attention.Although the big planet-forming ring around the star PDS 70 is clearly imaged and itself quite interesting.It's also not the planet on the right, just inside the big disk, that’s being talked about the most. Although the planet PDS 70c is a newly formed and, interestingly, similar in size and mass to Jupiter.It's the fuzzy patch around the planet PDS 70c that's causing the commotion.That fuzzy patch is thought to be a dusty disk that is now forming into moons -- and that had never been seen before.The featured image was taken in 2021 by the Atacama Large Millimeter Array (ALMA) of 66 radio telescopes in the high Atacama Desert of northern Chile. Based on ALMA data, astronomers infer that the moon-forming exoplanetary disk has a radius similar to our Earth's orbit, and may one day form three or so Luna-sized moons -- not very different from our Jupiter's four.