Caption: Second place in the 2021 IAU OAE Astrophotography Contest, category Galilean moons. This sequence shows the orbit of the four Galilean moons around the planet Jupiter. Almost two entire orbits of the innermost moon, Io, can be seen, with the other moons (Europa and Ganymede, but in particular Callisto) being further away, orbiting noticeably slower. The images were obtained in 2018 with the Las Cumbres Global Observatory at different locations on Earth, allowing a continuous sequence of images over approximately half a week without gaps during the day. With clear skies and over the course of several nights, the motion of the Galilean moons can also be observed with binoculars (ideally steady your elbows on a surface).
Credit: Nicolas Hurez, Paul-Antoine Matrangolo and Carl Pennypacker/IAU OAE

Caption: 2021 年国际天文学联合会 OAE 天体摄影比赛伽利略卫星类第一名。 这幅木星的延时摄影是于2017 年从德国拍摄的，作品精美地展示了伽利略卫星之一木卫一在木星前的凌星现象。由于这只是卫星在行星上投下影子，因此相当于从更远的地方观测地球上的月食。虽然卫星的影子从一开始就清晰可见，但在木星美丽的大气带背景下，第一次观看视频时可能很难发现卫星本身。反复观看可以欣赏到这一奇妙的快速运动和旋转过程。
Credit: Ralf Burkart/IAU OAE

Caption: 美国国家航空航天局的伽利略号航天器于1999年7月3日获得了木星卫星木卫一的最高分辨率图像。木卫一是伽利略-伽利雷 1610 年发现的四颗卫星之一。木卫一的颜色源于硫化物，是大量火山活动存在的证据。木星和邻近卫星的潮汐力是木卫一火山活动的原因。
Credit: 美国宇航局/JPL/亚利桑那大学 credit link