The Earth-Moon System 地月系统 A double planet? From 4 million miles away on December 16, 1992, NASA's robot spacecraft Galileo
took this picture of the Earth-moon system. The bright, sunlit half of the Earth contrasts strongly with the darker subdued colors of the moon. Our moon is one of the largest moons in the solar system. It is even larger than the planet Pluto. In this picture, the Earth-moon system actually appears to be a double planet. 一个双行星？1992年12月16日，在400万英里之外的美国航空航天局罗伯特飞船伽利略号拍到了这张地月系统的照片。地球朝向太阳的明亮一侧与暗淡的月球形成鲜明的对比。我们的月球是太阳系中最大的卫星，甚至比冥王星还要大。照片中，地月系统实际上看上去像一颗双行星。
Ida and Dactyl: Asteroid and Moon 爱达和载克太：小行星和卫星
An asteroid with a moon! The robot spacecraft Galileo
whose primary mission is to explore the Jupiter system, has encountered and photographed two asteroids during its long journey to Jupiter. The second asteroid it photographed, called Ida, was discovered to have a moon which appears as a small dot to the right of Ida in this picture. The tiny moon, named Dactyl, is about one mile across, while the potato shaped Ida measures about 36 miles long and 14 miles wide. Dactyl is the first moon of an asteroid ever discovered. The names Ida and Dactyl are based on characters in Greek mythology. 小行星也有卫星！罗伯特飞船伽利略号的主要使命是探索木星系统，但在通往木星的漫长旅途中，意外拍到了两颗小行星。它拍到的第二颗小行星命名爱达，人们发现它有一颗卫星，见图中爱达右侧的小点。这颗小卫星命名为载克太1号，直径约1英里，而马铃薯状的小行星爱达则有36英里长，14英里宽。载克太1号是迄今发现的首颗小行星卫星。爱达和载克太的名字来自希腊神话人物。
The Hooker Telescope on Mt. Wilson 威尔逊山的胡克望远镜 In the 1920s, pictures from the Hooker Telescope on Mt. Wilson fundamentally changed our understanding of the cosmos. Astronomer Edwin Hubble, using photographs he took with this telescope, demonstrated that the objects his contemporaries called "spiral nebulae" were actually huge systems of stars - spiral galaxies, similar to our own Milky Way galaxy but incredibly distant. Prior to Hubble's work it was argued that the spiral nebulae were mere clouds of gas and that they, along with everything else in the universe, were contained in our own galaxy. The Hooker Telescope mirror is 100 inches in diameter which is nearly the size of the mirror of the orbiting Hubble Space Telescope named in Hubble's honor. The Mount Wilson Observatory offers a "virtual walking tour" of this historic telescope. 19世纪20年代，威尔逊山的胡克望远镜拍摄的照片彻底改变了我们对宇宙的了解。天文学家爱德温哈勃利用这台望远镜拍下的照片证明，被同辈人称作“涡状星云”的物体实际上是个巨大的恒星系统-旋涡状星系，它和我们的银河系相似，却相隔异常遥远。胡克望远镜的镜片直径为100英尺，接近于以哈勃的名誉命名的哈勃轨道太空望远镜。威尔逊山的天文台提供了这台具有历史意义的望远镜的“虚拟徒步之旅”。 The Cartwheel Galaxy 车轮星系 The Cartwheel Galaxy shows a ring that is the result of a collision between a small and a large galaxy. After a small galaxy has moved through a big galaxy - in this case one that probably resembled our own Milky Way - a star formation wave moves out from the impact point like ripples across the surface of a pond. When galaxies collide it is rare that any two stars actually collide. Gravity, however, causes density waves to move out through the galaxy which in turn triggers the formation of hot, bright young stars, producing the ring that we see in this picture. 车轮星系呈现出大小两个星系碰撞而形成的光环。当一个小星系穿过大星系之后-在本例中如同我们的银河系-恒星形成的冲击波像池塘里涟漪的波纹一样，从撞击点荡漾开来。当星系发生碰撞时，很少会真正碰到一起。引力会使密度波穿透星系，继而形成炽热、耀眼的年轻恒星，产生我们在图片中看到的光环。 The Great Nebula in Orion 猎户座大星云
The Great Nebula in Orion, M42, can be found on the night sky just below and to the left of the easily identifiable belt of three stars in the popular constellation Orion. This nebula is one of the closest stellar nurseries - where young stars are being formed even now. Clumps of gas (mostly hydrogen and helium) and dust in the nebula are squeezed together by their own gravity until they collapse and form stars. Some stars we can see here partially obscured by the nebula, are only about 100,000 years old - just babies compared to the 5 billion (5,000,000,000) years of our Sun. 夜空下，由三颗星构成的著名猎户座的腰带很容易辨认，你可以在腰带的左下方找到猎户座大星云M42。它是最近的恒星摇篮，直到现在还有年轻的恒星在这里诞生。在星云内部，气团（主要为氢气和氦气）和尘埃因自身的引力相互挤压，直到瓦解并形成新的恒星。图片里我们看到一些部分被星云遮掩的恒星，年龄只有10万年左右，和我们太阳50亿年的年龄相比，简直就是婴儿。
The Firework Nebula 火焰星云
The Firework Nebula, known to astronomers as "GK Per", is the result of a type of stellar explosion called a nova. In a nova, a very compact star called a white dwarf blasts away gas that had accumulated on its surface. In this case the nova occurred in the year 1901 and is called Nova Persei 1901. This nova became as bright as one of the brighter stars we see in the night sky, but then faded until only a telescope could see it. Soon astronomers could see an expanding shell of gas that eventually became this spectacular nebula. The unusual "fireworks" type feature of this nebula is still a matter of research and discussion. 火焰星云，天文学家称为“GK Per”，是称一种称作新星的恒星爆炸的结果。新星内部，一颗叫白矮星的致密星将聚积在其表面的气团爆炸开来。图中的新星爆炸发生在1901年，这颗命名为新星深紫1901的新星成为夜空下我们所能看到的最亮的一颗星，但随后又暗淡到只有用望远镜才能看到。很快天文学家看到，不断扩张的气体外壳最终演变成图中壮观的星云。这颗新星不寻常的“火焰”状特征仍然是研究和讨论的课题。
The Night Side of Saturn 土星的夜半球
This image of Saturn was made in November 1980 by the Voyager1 spacecraft as it flew past the ringed gas giant planet. From a spectacular vantage point, looking back toward the inner solar system, the robot spacecraft recorded this view of the night side of Saturn casting a sharp shadow across the bright rings. No Earth based telescope could ever take a similar picture. Since Earth is closer to the sun than Saturn, only the day side of the planet is visible from the Earth. 这张土星照片是1980年旅行者1号飞船拍到的，当时飞船从这颗带光环的气体巨星旁边飞过。从壮观的有利位置，罗伯特飞船回望太阳系内部，拍到了土星的夜半球在明亮的光环上留下一道阴影。地球上没有一台望远镜可以拍到类似的照片。因为地球离太阳的距离比土星更近，在地球上只能看到土星的昼半球。
Saturn, Rings, and Two Moons 土星，光环和两颗卫星 This image of Saturn was made by NASA's robot spacecraft Voyager2 as it began to explore the Saturn system in 1981. Saturn's famous rings are visible along with two of its moons, Rhea and Dione which appear as faint dots in the right and lower right part of the picture. Astronomers believe that Saturn's moons play a fundamental role in sculpting its elaborate ring system. 1981年，美国航天航空局罗伯特飞船旅行者2号开始探索土星系统，并拍到这张土星照片。从图中我们可以看到有名的土星光环和右下方的两个暗点，即瑞亚和狄俄涅卫星。天文学家认为，土星的卫星在光环的形成中扮演着重要角色。
Lunar Farside from Apollo 13 从阿波罗13号上看到的月球远面 In April of 1970, after an explosion damaged their spacecraft, the Apollo 13astronauts were forced to abandon their plans to make the third manned lunar landing. Still, while coasting around the moon in their desperate attempt to return to earth they were able to photograph the moon's far side. The large, dark, smooth looking feature on the left in this picture is known as the "Mare Moscoviense". It was created by a lava flow filling in a large impact crater on the lunar surface. As suggested by the name, the Mare Moscoviense was first photographed by an early Soviet lunar probe. 1970年4月，阿波罗13号因一场爆炸受损，宇航员被迫放弃第三次月球着陆计划。但在试图返回地球的绕月飞行中，他们还能够拍到月球的远面。图片左侧，黑暗而光滑的巨大表面被称为“莫斯科海”，是由熔岩灌进月球表面的大陨石坑而形成的。“莫斯科海”的名字本身就暗示，它是苏联早期探月最先拍到的。 Damage to Apollo 13 受损的阿波罗13号
In April of 1970, after an oxygen tank exploded and damaged their service module, the Apollo 13astronauts were forced to abandon their plans to make the third manned lunar landing. The extent of the damage is revealed in this photo, taken as the crippled module was drifting away - jettisoned prior to their reentry and eventual safe splashdown. An entire panel on the right side of the module is seen to have been blown away and damage to internal structures is apparent. 1970年4月，因氧气瓶爆炸，服务舱受损，阿波罗13号飞船的宇航员被迫放弃第三次月球着陆计划。受损的服务舱抛放后，在漂移的过程中拍下了如图的受损情况。服务舱最终返回大气层，并安全降落。服务舱右翼的整块面板脱落，内部结构也明显受损。 | 
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