土星的一季

2023年8月25日

A Season of Saturn
Image Credit & Copyright: Andy Casely

Explanation: Ringed planet Saturn will be at its 2023 opposition, opposite the Sun in Earth’s skies, on August 27. While that puts the sixth planet from the Sun at its brightest and well-placed for viewing, its beautiful ring system isn’t visible to the unaided eye. Still, this sequence of telescopic images taken a year apart over the last six years follows both Saturn and rings as seen from inner planet Earth. The gas giant’s ring plane tilts from most open in 2018 to approaching edge-on in 2023 (top to bottom). That’s summer to nearly the autumn equinox for Saturn’s northern hemisphere. In the sharp planetary portraits, Saturn’s northern hexagon and a large storm system are clearly visible in 2018. In 2023, ice moon Tethys is transiting, casting its shadow across southern hemisphere cloud bands, while Saturn’s cold blue south pole is emerging from almost a decade of winter darkness.

Tomorrow’s picture: phases of Venus

土星的一季
影像提供与版权: Andy Casely

说明: 2023年8月27日，拥有行星环的土星将发生土星冲，于地球天空中与太阳180度反向。届时，这颗离太阳第六远的行星，将处在最明亮、非常适合观测的位置，不过肉眼并无法见到它美丽的环系。然而，这组摄于过去6年期间、每年拍摄一祯的望远镜影像系列，清楚呈现了在内行星地球所见到的土星和土星环。在影像里，这颗气态巨行星的行星环面，从2018年的最正向倾侧转变成2023年的接近侧向（从上到下）。对土星的北半球来说，季节也在这段期间从夏季来到了土星的秋分附近。在这幅清晰的行星影像里，于2018年之时，土星的北极六角云与大风暴系统清楚可辨。于2023年，冰卫星土卫三（Tethys）正在凌越土星，并把影子投射在南半球的云带上，而土星冰寒泛蓝的南极，也正从将近10年的冬季永夜中冒出头来。

明日的图片: phases of Venus