NGC 7009
土星星云（NGC 7009），是一个位于宝瓶座的行星状星云，威廉·赫歇耳于1782年使用20吋的反射望远镜所发现。土星星云是由于一个低质量的恒星演化成一个亮度11.5等的白矮星所形成的。 由于星云外表类似土星与它的环带，所以被称为土星星云。 因为星云附近没有可以做为参考的恒星，所以无法准确的计算出它与地球的距离，只知道大约在2000－4000光年之间。
Saturn Nebula
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Saturn Nebula NGC 7009
The Saturn Nebula or NGC 7009 is a planetary nebula in the constellation Aquarius. It appears as a greenish-yellowish hue in a small amateur telescope. It was discovered by William Herschel on September 7, 1782, using a telescope of his own design in the garden at his home in Datchet, England, and was one of his earliest discoveries in his sky survey. The nebula was originally a low-mass star that ejected its layers into space, forming the nebula. The central star is now a bright white dwarf star of apparent magnitude 11.5. The Saturn Nebula gets its name from its superficial resemblance to the planet Saturn with its rings nearly edge-on to the observer. It was so named by Lord Rosse in the 1840s, when telescopes had improved to the point that its Saturn-like shape could be discerned. William Henry Smyth said that the Saturn Nebula is one of Struve's nine "Rare Celestial Objects."
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