木星上的卫星影子

2022年4月27日

Moon Shadow on Jupiter
Image Credit: NASA/JPL-Caltech/SwRI/MSSS; Processing & License: Thomas Thomopoulos

Explanation: What is that large dark spot on Jupiter? It’s the shadow of Ganymede, Jupiter’s largest moon. When Jupiter’s moons cross between the Jovian giant and the Sun, they created shadows just like when the Earth’s moon crosses between the Earth and the Sun. Also like on Earth, if you were in a dark shadow on Jupiter, you would see a moon completely eclipse the Sun. Unlike on Earth, moon shadows occur most days on Jupiter — what’s more unusual is that a spacecraft was close enough to record one with a high-resolution image. That spacecraft, Juno, was passing so close to Jupiter in late February that nearby clouds and the dark eclipse shadow appear relatively large. Juno has made many discoveries about our Solar System’s largest planet, including, recently, rapidly expanding circular auroras.

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木星上的卫星影子
影像提供: NASA/JPL-Caltech/SwRI/MSSS; 影像处理与授权: Thomas Thomopoulos

说明: 木星上的那个大黑斑是什么？它是木星大卫星之一的木卫一之影子。当木星的卫星通过庞大的木星和太阳之间时，它们会产生阴影，情况和月亮穿过地球和太阳之间时雷同。而且类似在地球上，如果你位在木星表面的黝黑阴影里，你会看到太阳完全被卫星遮住。然而与地球有别的是：在木星上大部分的日子都会出现卫星的影子，而更不寻常的是，有一艘宇宙飞船靠得够近，得以用高解析率的影像把卫星的影子记录下来。这艘名为朱诺号的宇宙飞船，在二月底非常近距掠过木星，以至于邻近的云层和黝黑食影看来相对庞大。朱诺号对我们太阳系最大的行星有许多的新发现，包括最近发现木星有会迅速扩张的圆形极光。

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