http://antwrp.gsfc.nasa.gov/apod/ap061228.html
2006 December 28
Moon Over Andromeda
2006.12.28：仙女座大星系和月亮比大小
http://www.bjp.org.cn/files/2006-12/29/F_4ce497f86cee487f9c32902260c3aa20_m31abtpmoon.jpg
Credit & Copyright: Adam Block and Tim Puckett
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, M32and M110 (bottom).
仙女座大星系（缩写M31），离我们仅250万光年，是离我们银河系最近的巨型涡旋星系。在我们肉眼看来，M31是个昏暗的弥漫天体，由于（星盘）表面亮度太低，地球上的普通观星者感觉不到它是个壮观的天体。这张有趣的合成图像对比了这个近邻星系与我们更熟悉的明亮天体在天空中的视角大小。图中，深度曝光的M31照片展现了从明亮的黄色核心向外延伸的旋臂，上面缀满美丽的蓝色星团。作为对比，特别贴上了典型的满月图像。在同样的比例下，满月的视角约为0.5°，而M31明显比其大数倍。这幅M31的深空图像中还包括了它的两个明亮伴星系，位于上方的M32和下方的M110。
本帖最后由 gohomeman1 于 2010-2-18 00:38 编辑
客观的说，在肉眼看来，M31远不如满月大。
我很小的时候认识星空，那时的城市晚上天空还很纯净，银河清晰可见，秋夜看去，M31不过是昏暗的一块圆斑，其大小还不到月球的一半。对比上图就可知道，我看见的不过是其核心的最亮部分。
注意，上面这张对比图中的曝光时间完全不同，如果月球照片采用同样曝光条件、同样曝光时间，就是完全白亮的一大块了，根本分辨不出月海与山脉了。
同样的，我们用肉眼看天空，既使在最好观测条件下，也根本看不到照片中这么多的恒星。
还要说明一点的是，照片中的M31，不过是其明亮的星盘部分，其星系晕，延伸长度比图中还远2倍左右。
本帖最后由 gohomeman1 于 2010-2-18 00:49 编辑
http://antwrp.gsfc.nasa.gov/apod/ap070721.html
APOD 2007.7.21内容、图像与17楼的2006.6.9完全相同，在此补充一下红外图的配色等信息：
8.0微米：红
4.5微米：绿
3.6微米：蓝
视场：3.1X1.2平方度
CfA官网链接如下：
http://cfa-www.harvard.edu/
http://antwrp.gsfc.nasa.gov/apod/ap080124.html
2008 January 24
Andromeda Island Universe
2008.1.24：仙女座宇宙岛
http://www.bjp.org.cn/files/2008-01/24/F_9bcc00ecf06445c895bf0649bc7e0f3a_M31_hallas.jpg
Credit & Copyright: Tony Hallas
拍摄者、版权：Tony Hallas
Explanation:
The most distant object easily visible to the unaided eye is M31, the great Andromeda Galaxy some two and a half million light-years away. But without a telescope, even this immense spiral galaxy - spanning over 200,000 light years - appears as a faint, nebulous cloud in the constellation Andromeda. In contrast, a bright yellow nucleus, dark winding dust lanes, gorgeous blue spiral arms and star clusters are recorded in this stunning telescopic digital mosaic. While even casual skygazers are now inspired by the knowledge that there are many distant galaxies like M31, astronomers seriously debated this fundamental concept less than 90 years ago. Were these "spiral nebulae" simply outlying components of our own Milky Way Galaxy or were they instead "island universes" -- distant systems of stars comparable to the Milky Way itself? This question was central to the famous Shapley-Curtis debate of 1920, which was later resolved by observationsof M31 in favor of Andromeda, island universe.
肉眼可见的最遥远天体是M31——离我们约200万光年的巨大的仙女座大星系。不借助望远镜，既使这个跨度超过20万光年的庞大涡旋星系，也不过是仙女座内不起眼的昏暗云团而已。相比之下，在这张近邻宇宙岛漂亮的数码拼接图像中，可以清晰看到明亮的黄色核心、蜿蜒的黑色尘埃带、灿烂的蓝色旋臂和星团。虽然现在观星新手也知道，宇宙中有无数与M31类似的遥远星系；但是80年前，这样的基本概念在天文学界却争议极大：这些“螺旋型星云”到底是我们银河系外围的偏僻天体，还是它们与银河系一样，是遥远的“宇宙岛”？1920年，就此问题进行了著名的Shapley-Curtis辩论。后来一系列的观测表明，M31是遥远的“宇宙岛”。
上文虽然与6#楼文字雷同，但图像是不一样的。大家可以比较6#、16#与24#图像的异同，拍摄器材、人的技术进步，都起了作用。
本帖最后由 gohomeman1 于 2010-2-18 20:14 编辑
http://antwrp.gsfc.nasa.gov/apod/ap080909.html
2008 September 9
M110: Satellite of the Andromeda Galaxy
2008.9.9：仙女座大星系的伴星系：M110
http://www.bjp.org.cn/files/2008-09/09/F_83a34500d2d84e339d253c2b8fab760f_m110_cfht_big1.jpg
Credit & Copyright: Jean-Charles Cuillandre(CFHT) & Giovanni Anselmi(Coelum Astronomia),Hawaiian Starlight
版权：加拿大—法国—夏威夷合作天文台（CFHT）、Jean-Charles Cuillandre；以及相关夏威夷星空组织；相关网站（http://www.coelum.com/）、Giovanni Anselmi等
Explanation:
Our Milky Way Galaxy is not alone. It is part of a gathering of about 25 galaxies known as the Local Group. Members include the Great Andromeda Galaxy (M31), M32, M33, the Large Magellanic Cloud, the Small Magellanic Cloud, Dwingeloo 1, several small irregular galaxies, and many dwarf elliptical and dwarf spheroidal galaxies. Pictured on the lower right is one of the dwarf ellipticals: NGC 205. Like M32, NGC 205 is a companion to the large M31, and can sometimes be seen to the south of M31's center in photographs. The image shows NGC 205 to be unusual for an elliptical galaxy in that it contains at least two dust clouds (at 9 and 2 o'clock - they are visible but hard to spot) and signs of recent star formation. This galaxy is sometimes known as M110, although it was actually not part of Messier's original catalog.
我们的银河系并不孤单，它是本星系群的一员，成员共约25个，其他成员包括：仙女座大星系（M31）、M32，M33，大、小麦哲伦星系，以及Dwingeloo 1等数个不规则星系、多个矮椭圆星系、矮椭球星系等。图中左下显示的就是其中一个矮椭圆星系：NGC 205。与M32一样，它是巨大的M31的伴星系之一，在以M31为主题的照片中，能在核心区以南看见它。图中显示，NGC 205与普通的椭圆星系不同，在1点、7点方向至少各有一个尘埃云，并且有恒星在近期形成的迹象。NGC 205有时也称为M110，虽然它并未收录在原始的梅西耶星云星团表中。
由于我贴的是原始大图，所以方向与说明的有些不同，翻译中已经予以纠正，但并未修改英文。
本帖最后由 gohomeman1 于 2010-2-18 22:22 编辑
http://antwrp.gsfc.nasa.gov/apod/ap090510.html
2009 May 10
M31: The Andromeda Galaxy
2009.5.10：仙女座大星系M31
http://www.phys.ncku.edu.tw/%7Eastrolab/mirrors/apod/image/0905/m31_gendler_big.jpg
Credit & Copyright: Robert Gendler
拍摄者、版权：Robert Gendler
Explanation:
Andromeda is the nearest major galaxy to our own Milky Way Galaxy. Our Galaxy is thought to look much like Andromeda. Together these two galaxies dominate the Local Group of galaxies. The diffuse light from Andromeda is caused by the hundreds of billions of stars that compose it. The several distinct stars that surround Andromeda's image are actually stars in our Galaxy that are well in front of the background object. Andromedais frequently referred to as M31 since it is the 31st object on Messier's list of diffuse sky objects. M31 is so distant it takes about two million years for light to reach us from there. Although visible without aid, the above imageof M31 is a digital mosaic of 20 frames taken with a small telescope. Much about M31 remains unknown, including how it acquired its unusual double-peaked center.
仙女座大星系M31是离我们最近的大型星系。一般认为，我们的银河系与仙女座大星系很相似，它们两者在本星系群中处于支配地位。M31撒播的光来自其中的数千亿颗恒星，而图像中M31周围的大量明亮群星是我们银河系中该方向的前景星。M31的名称来自它是梅西耶弥漫天体表中的第31#，它相当“遥远”，来自它的星光需要200万年以上才能到达我们这里。M31中还有大量未解之谜，包括它为何有2个核心。
PS：本文再次与4#楼完全一样，但是大师提供了新的图像——gohomeman1注
http://antwrp.gsfc.nasa.gov/apod/ap090917.html
2009 September 17
Ultraviolet Andromeda
2009.9.17：仙女座大星系的紫外光图像
http://www.phys.ncku.edu.tw/%7Eastrolab/mirrors/apod/image/0909/UVAndromeda_swiftH600.jpg
http://www.phys.ncku.edu.tw/%7Eastrolab/mirrors/apod/image/0909/OpticalAndromeda_h600.jpg
Credit: UV - NASA/Swift/Stefan Immler(GSFC)and Erin Grand (UMCP)
紫外光图像版权：美国宇航局（NASA），雨燕高能射线卫星，戈达德太空飞行中心（GSFC） 斯蒂芬.Immler，马里兰州立大学帕克学院（UMCP） Erin Grand等
Optical - Bill Schoening, Vanessa Harvey/REU program/NOAO/AURA/NSF
可见光图像版权：比尔.Schoening、瓦妮莎.哈维；本科生科研经验（REU）项目；国家光学天文台（NOAO）；大学天文研究联合机构（AURA）；国家科学基金会（NSF）
Explanation:
Taken by a telescope onboard NASA's Swift satellite, this stunning vista represents the highest resolution image ever made of the Andromeda Galaxy (aka M31) - at ultraviolet wavelengths. The mosaic is composed of 330 individual images covering a region 200,000 light-years wide. It shows about 20,000 sources, dominated by hot, young stars and dense star clusters that radiate strongly in energetic ultraviolet light. Of course, the Andromeda Galaxy is the closest large spiral galaxy to our own Milky Way, at a distance of some 2.5 million light-years. To compare this gorgeous island universe's appearance in optical light with its ultraviolet portrait, just slide your cursor over the image.
这是NASA的雨燕高能卫星上的望远镜拍摄的仙女座大星系（M31）的组合图像，这张迄今为止紫外光波段最高清晰度的迷人全景图，是由330张单图拼合而成，覆盖了20万光年的天区。其中显示了约2万个辐射源，主要是发出强烈紫外辐射的炽热年轻巨星和密集的星团。当然啦，M31离我们仅250万光年，是离银河系最近的巨型涡旋星系。要比较这个壮丽宇宙岛的可见光与紫外光图像，就把鼠标移到图像上吧！
PS：没必要这么复杂，我直接贴出2张图就更方便了——gohomeman1注
与红外图一样，在北方区域，有个巨大的空洞，但在可见光图像上就不明显。看这张巨图：
http://www.bjp.org.cn/files/2009-09/17/F_54fad88f26d3449fb9427397b6ac83f6_Swift_M31_large_UV70p.jpg
这是最新公布的M31的红外图，估计几天后APOD会发的，我就先贴在这里，APOD发的时候再注解一下吧，今天的CCTV1中已经提到了。
http://www.nasa.gov/mission_pages/WISE/multimedia/pia12832-c.html
02.17.10
Our Neighbor Andromeda
2010.2.17：我们的近邻——仙女座大星系的红外光图像
http://www.nasa.gov/images/content/427006main_pia12832-c516.jpg
The immense Andromeda galaxy, also known as Messier 31 or simply M31, is captured in full in this new image from NASA's Wide-field Infrared Survey Explorer, or WISE. The mosaic covers an area equivalent to more than 100 full moons, or five degrees across the sky. WISE used all four of its infrared detectors to capture this picture (3.4- and 4.6-micron light is colored blue; 12-micron light is green; and 22-micron light is red). Blue highlights mature stars, while yellow and red show dust heated by newborn, massive stars.
NASA的广域红外巡天探测器（WISE）拍摄了庞大的仙女座大星系（又称梅西耶31#天体，缩写M31）的最新红外光全图。这张拼接图像的视场面积超过100个满月，相当于5平方度的天区。WISE使用了它全部4个红外通道以获取此图像，它们的配色如下：3.4、4.6微米，蓝；12微米，绿；22微米，红。蓝色突出显示成熟的老年恒星，而红色、黄色则表示被新形成的大质量恒星加热的尘埃辐射。
Andromeda is the closest large galaxy to our Milky Way galaxy, and is located 2.5 million light-years from our sun. It is close enough for telescopes to spy the details of its ringed arms of new stars and hazy blue backbone of older stars. Also seen in the mosaic are two satellite galaxies, known as M32, located just a bit above Andromeda to the left of center, and the fuzzy blue M110, located below the center of the great spiral arms. These satellites are the largest of several that are gravitationally bound to Andromeda.
M31离太阳约250万光年，是离银河系最近的巨型星系。它离我们如此之近，足够望远镜解析出年轻恒星组成的环状旋臂和老年恒星组成的朦胧蓝色背景晕的细节。图中还能看到M31的两个伴星系，其中M32是位于M31中心左上的蓝色小斑点，而M110是位于下方的蓝色模糊团块。它们是被M31引力束缚的矮星系中最大的2个。
The Andromeda galaxy is larger than our Milky Way and contains more stars, but the Milky Way is thought to perhaps have more mass due to its larger proportion of a mysterious substance called dark matter. Both galaxies belong to our so-called Local Group, a collection of more than 50 galaxies, most of which are tiny dwarf systems. In its quest to map the whole sky, WISE will capture the entire Local Group.
M31比银河系大，也包含更多的恒星。不过，现在也有认为银河系更重的，原因是它含有巨量的神秘物质——暗物质。银河系和仙女座大星系主宰了本星系群，它是一个含有50个以上星系的集群，当然大部分是微型矮星系。在WISE的全天空巡天历程中，它将拍摄整个本星系群的图像。
Image credit: NASA/JPL-Caltech/UCLA
图像版权：美国宇航局（NASA），加州理工学院，喷气推进实验室（JPL），加州大学洛杉矶分校（UCLA）
我之所以给出小图，是因为WISE的jpg大图也太大了，都在14MB以上，现在的网络还不能流畅地显示它们。
http://www.nasa.gov/images/content/427008main_pia12833-c1-516.jpg
这是3.4微米波段拍摄的M31，可以看到北方（左上）区域的旋臂有个明显的扭曲，这是引力扰动的结果。注意，蓝色代表的是老年恒星，不是年轻恒星。
http://www.nasa.gov/images/content/427011main_pia12834-c2-516.jpg
这是12、22微米红外波段拍摄的M31，其中12微米配色橙，22微米配色红。注意，红色、橙色代表被年轻恒星加热的尘埃辐射。可以看到，M32、M110的中心区域也存在少量尘埃。
WISE最新的M31大图下载：
四个红外波段合成图像：
http://www.nasa.gov/images/content/427020main_pia12832-c.jpg，6666X6666，14.1MB
3.6微米波段单色图像（蓝）：
http://www.nasa.gov/images/content/427021main_pia12833-c1.jpg，同上，15.6MB
12微米、22微米合成图像（不大，就直接贴了）：
http://www.nasa.gov/images/content/427066main_pia12834-c2-full.jpg
明晚来发哈勃拍摄的M31，它是精细图像，但不是全貌。
此贴太棒了，辛苦了！
辛苦了！！！！！！
m31，想起了圣斗士星矢
nice~很清晰很详细 3Q楼主
很好，收大图了~~