三重过境和相互事件
(原标题: Triple Transit and Mutual Events)
2021-08-21
浏览次数: 63
这三个展板展示了8月15日在菲律宾宿雾市从地球上看到的太阳系的气态巨行星木星。在那一天，天文望远镜精确地观测了木星的伽利略卫星的一些非凡的表现，凌日和相互事件。在上图中，木卫一正消失在木星最右边的阴影中，但木星的其他三个大卫星则出现在木星的带状圆盘上。较亮的木卫二和较暗的木卫三在最左边，它们的两个影子也投射在这颗气体巨星的云顶上。木卫四位于木星边缘的下方和附近，这三颗卫星在木星表面进行三次凌日。移动到中间的面板，木卫二和木卫三的阴影仍然可以在靠近中心的地方看到，但木卫三已经被木卫二遮挡或从木卫二面前经过。底部的画面捕捉到了罕见的木星卫星经过木星时的日食景象，木卫三的影子落在木卫二上。从地球的角度来看，类似的相互事件，即伽利略的卫星相互隐藏和日食，每隔六年左右，当木星接近它自己的春分时，就可以看到。
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These three panels feature the Solar System's ruling gas giant Jupiter on August 15 as seen from Cebu City, Philippines, planet Earth. On that date the well-timed telescopic views detail some remarkable performances, transits and mutual events, by Jupiter's Galilean moons. In the top panel, Io is just disappearing into Jupiter's shadow at the far right, but the three other large Jovian moons appear against the planet's banded disk. Brighter Europa and darker Ganymede are at the far left, also casting their two shadows on the gas giant's cloud tops. Callisto is below and right near the planet's edge, the three moons in a triple transit across the face of Jupiter. Moving to the middle panel, shadows of Europa and Ganymede are still visible near center but Ganymede has occulted or passed in front of Europa. The bottom panel captures a rare view of Jovian moons in eclipse while transiting Jupiter, Ganymede's shadow falling on Europa itself. From planet Earth's perspective, similar mutual events, when Galilean moons occult and eclipse each other, can be seen every six years or so when Jupiter is near its own equinox.
© Christopher Go