Caption: Winner in the 2022 IAU OAE Astrophotography Contest, category Still images of celestial patterns.   As Earth moves around the Sun, the positions of the stars in the night sky appear to change over the course of the year. This is well exemplified in this mosaic, with images taken in all four seasons throughout 2020 in the region of Veneto, Italy, showing the apparent motion of the Ursa Minor and Ursa Major constellations. Ursa Minor, the Little Bear, is a constellation of the northern hemisphere, and it contains the northern celestial pole, in our current epoch marked by a bright star called Polaris or the Pole Star. For centuries Polaris has been used for navigation in the northern hemisphere, as it has been almost at the exact pole position for roughly 200 years. In the Middle Ages and antiquity, there was no pole star; the celestial north pole lay in a dark region and the Greeks considered the “Little She-Bear” as a companion of the “Great She-Bear”, which is more easily recognizable. The brightest stars of these constellations were alternatively also considered as chariots by the Greeks, as written in Aratus’s famous didactic poem from the 3rd century before the common era. The most famous asterism in Ursa Major, composed of seven stars, has different names across the (northern) world. While considered as a chariot by the Greeks, it is “The Northern Dipper” in China, and “The Seven Oxen” for the ancient Romans. It was also the navigational purpose that led to the name The Great She-Bear, Ursa Major; for the Greeks, travelling towards the direction of the horizon above which Ursa Major appears meant moving towards the land of the bears (northern Europe). An animal is clearly recognizable when taking into account all the fainter stars in the vicinity of the seven bright ones. They considered it a female bear because Greek mythology connects this animal with the nymph Callisto, whose story describes the initiation rituals for women. In the top left, we see an image taken on a spring evening, while the image below shows the same portion of the sky on a summer evening. Going counterclockwise, we see the sky during autumn in the bottom right image, while the top right finally shows this portion of the sky in the winter. Note that the relative positions of Ursa Minor and the Big Dipper don’t change, but all stars appear to be moved in a circle around Polaris. This star pointing due north lies at the point where Earth’s rotational axis intersects the celestial sphere. The shift of constellations throughout the year is therefore a globe-clock or a globe-calendar, used by ancient civilizations to measure the year, and to predict the changes of seasons. It helps to establish, for instance, the best time for sowing and sailing as winds change with the seasons.
Credit: Giorgia Hofer/IAU OAE

Caption: 这张令人叹为观止的照片是 2020 年 6 月 25 日在印度尼西亚西爪哇库宁安省西里穆斯市凌加梅卡村的晴朗夜空下拍摄的，照片中的星轨掠过南半球的天际。星轨是地球自转所导致的恒星表观运动，当长时间跟踪时，就会产生这些令人着迷的光弧。因为这张照片是在赤道附近拍摄的，所以恒星所围绕旋转的点（南天极）靠近地平线。摄影师使用智能手机上的星轨功能，在较长时间内拍摄了一系列图像，并将它们叠加在一起。前景引人注目的大树增添了画面的深度，使上方天体的运动与地面的静止形成了鲜明对比，同时也遮掩了周围的一些光污染。世界不同地区的夜空景色各异，令人惊叹，使人们意识到保护各地黑暗天空的重要性。
Credit: Slamat Riyadi/IAU OAE (CC BY 4.0)

Caption: 这段视频展示了银河在茫茫星空中的璀璨光芒。在群星的大剧场中，南十字星座占据了一席之地，其独特的十字形状在本视频的顶部可见，就在银河系上方，稍微向右。随着视频的推进，南十字座慢慢消失在视野。这个天文记号是南半球的一个突出特征，具有文化和导航意义，几个世纪以来一直是航行路标。与银河的壮观相伴的是两朵麦哲伦云，它们是在遥远天空中翩翩起舞的伙伴。船底座星云为宇宙全景增添了空灵缥缈的光辉，在黑暗中描绘出一种璀璨的色调。在这场天体芭蕾中，温和的绿色笼罩着大气层，这种现象被称为 "气辉"，为夜空增添了一抹微妙的荧光。地面上也有飞机从头顶飞过和车辆在天文台建筑之间行驶的景象。这幅延时摄影是从智利的拉西亚天文台拍摄的，它是一扇通往迷人星舞的窗口，让我们得以一窥银河系令人惊叹的美景和南天的地标。
Credit: José Rodrigues/IAU OAE (CC BY 4.0)

Caption: 这幅延时摄影作品拍摄于 2023 年 6 月从智利圣佩德罗德阿塔卡马，展现了南十字星在夜空中壮丽的旅程，指引着南天极周围的天空旋转，直到它优雅地落下。满天繁星的画布展示了银河的壮丽，以及围绕南天极旋转的大麦哲伦云和小麦哲伦云。显著的星座包括十字、半人马座、天蝎座和以前的阿尔戈船座（船尾座、帆座、船座）也都可见。整个景象在夜幕降临后不久开始，捕捉到坎普斯星的耀眼下降，这颗明亮的星星即将沉入地平线。在序列中，可以隐约看到经过的飞机、闪烁的汽车车灯、漂浮的云朵以及神秘的空气辉光。在一个惊艳的时刻，一颗流星划过天空，璀璨的火球在大约第41秒时短暂点亮画面的右下角。随着序列的发展，升起的月亮优雅地照亮了风景，把光辉洒在静卧于阿塔卡马盐滩干燥尘土中的古老树干上。这段迷人的夜空之旅在黎明前结束，提供了一瞥交织在圣佩德罗·阿塔卡玛夜晚风景中的天体奇迹。
Credit: Uwe Reichert/IAU OAE (CC BY 4.0)

Caption: 这段延时摄影捕捉了来自国家天体物理研究所 (INAF) 的 64 米撒丁岛射电望远镜 (SRT) 周围的恒星运动，特别是在天球背景下著名的北斗七星。随着飞机飞过和射电望远镜旋转，著名的北斗七星在天空中下沉，镜头也随之移动。恒星的轨迹与射电望远镜的巨大天线之间的和谐互动，为 2019 年 9 月拍摄的宇宙芭蕾谱写了一曲令人着迷的视觉颂歌。
Credit: Antonio Finazzi/IAU OAE (CC BY 4.0)

Caption: 这张拍摄于2022年10月的照片是在印度阿马尔提亚村（Amartiya）帕诺提耶（Panotiya）的黑夜中拍摄的，展现了夜空中美丽的星轨。摄影师仅用一部智能手机和一个三脚架就捕捉到了这些星轨——它们是我们星球自转的视觉证据，因为每一条星轨都代表着地球自转时恒星的明显运动，创造出令人着迷的宇宙光影编舞。恒星有不同的颜色，有的闪着蓝光，有的泛白，暗示着它们不同的温度和组成。此外，一架飞机的细微轨迹与永恒的星空之舞短暂的交汇在一起，宁静的星空与下方熙熙攘攘的生命活动形成了鲜明对比。
Credit: Govind Gurjar/IAU OAE (CC BY 4.0)

Caption: 北斗七星优雅地移动于加利福尼亚州莫诺湖超凡脱俗的凝灰岩层之上。延时摄影捕捉了北斗七星穿过北方地平线直至下合的过程。在莫诺湖的纬度（+38°）上，北斗七星的星星几乎都是环极星，除了阿尔凯德（Alkaid）。北极星位于地平线之上38°的位置，正好在视野的右上角之外。月光将大地笼罩在柔和的光晕中，随着月亮落下，光晕逐渐变暗，整个场景陷入黑暗之中。
Credit: Fabrizio Melandri/IAU OAE (CC BY 4.0)

Caption: A cosmic journey unfolds across continents in this time-lapse video which captures both iconic constellations from diverse corners of the world. Starting in China, the Big Dipper graces the night sky, a steadfast guide embedded in cultural narratives. Its luminance marks the beginning of this celestial odyssey. The two pointer stars on the end of the Big Dipper point to the North Star (Polaris) which appears to remain stationary as the sky rotates. From Nepal’s lofty peaks, the Big Dipper’s familiarity persists, a reliable fixture in the shifting panorama of the rotating planet. Moving to Chile, the Southern Cross adorns the firmament, emblematic of the southern skies. Frames from Chile showcase this constellation accompanied by the Milky Way Galaxy. In Namibia, a telescope from the H.E.S.S. Observatory appears in the video. Later, nestled beneath sheltering trees, the Big Dipper persists in its celestial prominence, appearing against a canvas of stars. Using varied techniques — fisheye lenses, static cameras, and Earth's movement-tracking — each frame unveils the Cross’s grandeur against diverse landscapes. These sequences — marked by star trails and Earth’s rotation—highlight the enduring presence of the Big Dipper and Southern Cross, bridging cultures and celestial beauty across hemispheres.
Credit: Jianfeng Dai/IAU OAE (CC BY 4.0)