2025年9月22日
Equinox at Saturn
Image Credit & Copyright: Imran Sultan
Explanation: On Saturn, the rings tell you the season. On Earth, today marks an equinox, the time when the Earth’s equator tilts directly toward the Sun. Since Saturn’s grand rings orbit along the planet’s equator, these rings appear most prominent — from the direction of the Sun — when the spin axis of Saturn points toward the Sun. Conversely, when Saturn’s spin axis points to the side, an equinox occurs, and the edge-on rings are hard to see from not only the Sun — but Earth. In the featured montage, images of Saturn between the years of 2020 and 2025 have been superposed to show the giant planet passing, with this year’s equinox, from summer in the north to summer in the south. Yesterday, Saturn was coincidently about as close as it gets to planet Earth, and so this month the ringed giant’s orb is relatively bright and visible throughout the night.
Tomorrow’s picture: cathedral to massive stars
土星的春分
影像提供与版权: Imran Sultan
说明: 土星的光环可以告诉你季节。在地球上，今天是春分，也是地球的赤道直接朝向太阳的时刻。由于土星的壮观光环位于行星的赤道面上，当土星的自转轴指向太阳时，环状结构从太阳方向看最为明显。相反地，当土星的自转轴指向侧面时，会发生春分(太阳指向土星赤道)，此时不仅从太阳，而且从地球的角度来看，都很难看到侧向的光环。在特色拼贴中，展示了从2020年到2025年之间的土星影像，这些影像被叠加以显示这颗巨大的行星在今年的春分中，从北半球的夏季过渡到南半球的夏季。昨天，土星恰巧接近离地球最近的距离，因此本月这颗带环的巨型球体相对明亮，并且整夜可见。
明日的图片: cathedral to massive stars
