57 Galileo's Moons-Mid

Galileo's Moons FOCUS Question What makes each of Jupiter's four largest moons unique?

伽利略的卫星焦点问题是什么让木星的四个最大的卫星各有独特之处?

Many Moons When you look up at the sky, you may see the Moon. It is Earth's only moon. But Jupiter has more than sixty moons, and counting! The four largest are known as the Galilean moons. They are named for Galileo Galilei, who discovered them in 1610. Why so many moons? Jupiter is the largest planet in the solar system. More than one thousand planets the size of Earth would fit inside Jupiter! Because of its massive size, Jupiter has very strong gravity. Dust, gases, asteroids, and space debris got pulled into orbit around Jupiter by this strong gravity. This material clumped together to form Jupiter's many moons. Do You Know? Galileo spotted four of Jupiter's moons using a telescope he made himself. His scope could see objects three times farther away than other telescopes of the time.

当你仰望天空时，你可能会看到月亮。 它是地球唯一的卫星。但是木星有六十多颗卫星，而且还在增加!最大的四颗卫星被称为伽利略卫星。 它们以1610年发现它们的伽利略·伽利莱命名。 为什么有这么多卫星?木星是太阳系中最大的行星。 超过一千颗地球大小的行星可以装进木星!由于木星巨大的体积，它有很强的引力。 尘埃、气体、小行星和太空碎片被强大的引力拉进了木星周围的轨道。 这些物质聚集在一起形成了木星的许多卫星。 你知道吗?伽利略用自己制作的望远镜发现了木星的四颗卫星。 他的望远镜能看到比当时其他望远镜远三倍的物体。

Meet the Moons The Galilean moons are Europa, Io, Callisto, and Ganymede. Europa (yuh-ROW-puh) is the smallest of the four moons. Io (EYE-oh) is a little larger than Europa. Callisto (kuh-LIH-stow) is about the same size as the planet Mercury. The largest is Ganymede (GA-nuh-meed), which is even larger than Mercury. Their orbits around Jupiter are very short compared to the orbit of Jupiter around the Sun. Use the chart to compare these four moons. Galilean Moons Europa Io Callisto Ganymede Diameter (km) 3,138 3,630 4,800 5,262 Distance from Jupiter (millions of km) 0.671 0.422 1.883 1.070 Orbital Period (days) 3.6 1.8 16.7 7.2

伽利略的卫星有木卫二、木卫一、木卫四和木卫三。 木卫二(yuh-ROW-puh)是四个卫星中最小的一个。 木卫一(EYE-oh)比木卫二稍大。 木卫四(kuh-LIH-stow)和水星差不多大。 最大的是Ganymede (GA-nuh-meed)，它比水星还要大。 与木星围绕太阳的轨道相比，它们围绕木星的轨道非常短。 用图表来比较这四个月亮。 伽利略卫星木卫二木卫一木卫四木卫三木卫三直径(公里)3,138 3,630 4,800 5,262离木星的距离(百万公里)0.671 0.422 1.883 1.070公转周期(天)3.6 1.8 16.7 7.2

Europa Scientists want to know more about Europa because it could have life! Europa's surface is covered in ice. But beneath the ice may be a liquid ocean. In 1998, the Galileo spacecraft found signs of liquid water on Europa. The spacecraft took pictures of cracks in the ice. Scientists think that the cracks were caused by moving water below the ice. Most of Earth's life is found in the ocean. The same may be true of Europa. The Hubble Space Telescope recorded water vapor spewing from Europa's surface in 2013. This gives scientists more hope of finding liquid water on that moon. Wowser! Scientists crashed the Galileo spacecraft into Jupiter on purpose Why? They didn't want it to crash on Europa and possibly harm any life in its ocean.

科学家们想要更多地了解木卫二，因为它可能有生命!木卫二表面覆盖着冰。 但在冰层之下可能是一个液态海洋。 1998年，伽利略号宇宙飞船在木卫二上发现了液态水的迹象。 宇宙飞船拍下了冰裂缝的照片。 科学家认为这些裂缝是由冰下流动的水造成的。 地球上的大部分生命都在海洋中。 木卫二可能也是如此。 2013年，哈勃太空望远镜记录下了欧罗巴表面喷出的水蒸气。 这让科学家们更有希望在这颗卫星上找到液态水。 老古板!科学家故意将伽利略号宇宙飞船撞向木星为什么? 他们不希望它撞到木卫二上，可能会伤害到海洋中的任何生命。

EUROPA: A RECIPE FOR LIFE? If we could find living things—even very simple life forms—beyond Earth, it would be very exciting! Scientists think several "ingredients" are needed for life to exist. Does Europa have them? 1. Is there water? Yes! Scientists believe Europa has a vast saltwater ocean beneath its icy surface. 2. Is the temperature just right? Yes! The climate needs to be warm enough for liquid water to flow but not too hot. As with Io, friction caused by the gravitational tug of Jupiter and other moons may keep water below the surface liquid. But Europa is not fiery like Io. 3. Does it contain the building blocks of life? Yes! Probes have found signs of organic, or living, compounds.

木卫二:生命的秘方? 如果我们能在地球之外找到生物，哪怕是非常简单的生命形式，那将是非常令人兴奋的!科学家认为生命的存在需要几种“成分”。 木卫二上有吗?1. 有水吗? 是的!科学家们认为木卫二冰冷的表面下有一个巨大的咸水海洋。 2. 温度刚刚好吗? 是的!气候需要足够温暖，让液态水流动，但又不能太热。 与木卫一一样，木星和其他卫星的引力牵引引起的摩擦可能会使表面以下的水保持液态。 但是木卫二不像木卫一那样炽热。 3.它包含生命的组成部分吗? 是的!探测器已经发现了有机化合物的迹象。

Io Closest to Jupiter, Io is covered with active volcanoes. In 1979, the Voyager spacecraft took pictures of volcanoes erupting. Lava from the volcanoes flows over Io's surface. Some places have hot spots, which may be lakes of lava. The atmosphere is a poisonous mix of gases given off by the eruptions. Io may be such a fiery place because of the way Jupiter "tugs" on it. The mighty planet's strong pull on Io causes materials inside the moon to rub together. All that friction heats Io up from the inside. Try This Rub your hands together as fast as you can. The rubbing causes friction. Are your hands getting warm? Friction gives off heat.

木卫一离木星最近，布满了活火山。 1979年，旅行者号宇宙飞船拍摄到了火山喷发的照片。 火山喷出的熔岩在木卫一表面流动。 有些地方有热点，可能是熔岩湖。 大气是火山喷发释放出的有毒气体的混合物。 木卫一之所以是一个如此火热的地方，可能是因为木星对它的“牵引”。 这颗强大的行星对木卫一的强大引力使其内部的物质相互摩擦。 所有的摩擦从内部加热木卫一。 试着用最快的速度搓你的手。 摩擦产生摩擦。 你的手暖和了吗? 摩擦散发热量。