版权： Adam Block and Tim Puckett
说明：距离我们只有250万光年的仙女大星系(又称为M31)，是距离我们银河系最近
的大型旋涡星系。用肉眼看去，仙女座大星系是一个昏暗而弥漫的小斑块，由于它的
表面亮度极低，一般的观星人感受不到它在地球天空中其实应该是一个很壮观的天
体。上图这幅有趣的组合影像，用我们较熟悉的月亮来表现这个邻近星系的真实视张
角之大小。在这幅仙女座大星系的深场影像里，我们可以看到镶在从亮黄色星系核向
外伸展的旋臂中的蓝色星团，以及特别嵌入的一轮明月。月亮大约涵盖了半度的天
区，仙女座大星系明显要比月亮大上数倍。在这幅仙女座大星系的深场影像里，还可
以见到两个明亮的卫星星系，即中上方的M32和左下角的M110。
原文来自： http://antwrp.gsfc.nasa.gov/apod/ap061228.html
译文来自：http://www.astron.sh.cn/picbase/daily/070309/070309.htm
(上海网上天文台 cliff编译)
原文：
Explanation: The Great Spiral
Galaxy in Andromeda (aka M31), a mere 2.5 million light-years
distant, is the closest large spiral to our own Milky Way. Andromeda is visible to the unaided eye as a small, faint, fuzzy patch, but because its surface brightness is so low, casual
skygazers can't appreciate the galaxy's impressive extent in planet Earth's sky. This entertaining composite image compares the
angular size of the nearby galaxy to a brighter, more familiar celestial sight. In it, a
deep exposure of Andromeda, tracing beautiful blue star clusters in spiral arms far beyond the bright yellow core, is combined with a typical view of a nearly full Moon. Shown at the same angular scale, the Moon covers about 1/2 degree on the sky, while
the galaxy is clearly several times that size. The deep Andromeda exposure also includes two bright satellite galaxies,
M32 and
M110 (bottom).
图片大小：2.17MB
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本帖最后由 活动星图 于 2007-3-11 17:14 编辑 ]
