2020年08月06日:M20与M21-（Messier 20 and 21） 2020年08月06日:M20与M21-（Messier 20 and 21）--原图下载{mtitle title="M20与M21"/}Image Credit &Copyright:Emanuele Petrilli说明: 亦名为M20的美丽三叶星云，位在星云密布的人马座之内，是一个用小望远镜即可轻易找到的天体。在这张跨幅将近1度的影像里，距离约5,000光年远的三叶星云，与疏散星团M21（右）分享了这片取景佳妙的视野，形成了探索天体对比的彩色案例。被尘埃带割成三片的三叶星云，大小约为40光年，年龄只有300,000年左右。因此，它是我们天空中最年轻的恒星形成区之一，其内的新生恒星和胎星仍然包裹在孕育它们的尘埃和云气里。而距离和M20相当的疏散星团M21，内部恒星的年龄则是远较年长的8百万年。虽然它们分享这片壮丽的望远镜星野，不过，它们二者之间并无明显的关联。{lamp/}原文：{mtitle title="Messier 20 and 21"/}Image Credit &Copyright:Emanuele PetrilliExplanation: The beautiful Trifid Nebula,also known as Messier 20, is easytofind with a small telescope in the nebula rich constellationSagittarius.About 5,000 light-years away, the colorful study incosmic contrasts sharesthis well-composed, nearly 1 degree wide field withopen star clusterMessier 21(right).Trisected by dust lanesthe Trifid itself is about 40 light-years across anda mere 300,000 years old.That makes it one of theyoungest starformingregions in our sky,with newborn and embryonic stars embedded in itsnatal dust and gas clouds.Estimates of the distance to open star cluster M21 are similar to M20's,but though they share this gorgeous telescopic skyscapethere is no apparent connection between the two.In fact, M21's stars are much older, about 8 millionyears old.

2019年12月30日:M20与M21-（Messier 20 and 21） 2019年12月30日:M20与M21-（Messier 20 and 21）--原图下载{mtitle title="M20与M21"/}Image Credit &Copyright: Stanislav Volskiy,Chilescope Team说明: 亦名为M20的美丽三叶星云，位在星云密布的人马座之内，是一个用小望远镜即可轻易找到的天体。在这张跨幅将近1度的影像里，距离约5,000光年远的三叶星云，与左上角的疏散星团M21分享了这片取景佳妙的视野，形成了探索天体对比的彩色案例。 被尘埃带割成三片的三叶星云，大小约为40光年，年龄只有300,000年左右。 因此，它是我们天空中最年轻的恒星形成区之一，其内的新生恒星和胎星仍然包裹在孕育它们的尘埃和云气里。 而估计距离和M20相当的疏散星团M21，内部恒星的年龄是远较年长的8百万年。 虽然它们分享这片壮丽的望远镜星野，不过，它们二者之间并无明显的关联。{lamp/}原文：{mtitle title="Messier 20 and 21"/}Image Credit &Copyright: Stanislav Volskiy,Chilescope TeamExplanation: The beautiful Trifid Nebula,also known as Messier 20, is easytofind with a small telescope in the nebula rich constellationSagittarius.About 5,000 light-years away, the colorful study incosmic contrasts sharesthiswell-composed, nearly 1 degree wide field withopen star clusterMessier 21(top left).Trisected by dust lanesthe Trifid itself is about 40 light-years across anda mere 300,000 years old.That makes it one of theyoungest starformingregions in our sky,with newborn and embryonic stars embedded in itsnatal dust and gas clouds.Estimates of the distance to open star cluster M21 are similar to M20's,but though they share this gorgeous telescopic skyscapethere is no apparent connection between the two.In fact, M21's stars are much older, about 8 millionyearsold.

2018年08月24日:梅西叶20与21-（Messier 20 and 21） 2018年08月24日:梅西叶20与21-（Messier 20 and 21）--原图下载{mtitle title="梅西叶20与21"/}Image Credit &Copyright:IgnacioDiaz Bobillo说明: 亦名为M20的美丽三叶星云，位在星云密布的人马座之内，是一个小望远镜轻易可见的天体。在这张跨幅1度的影像里，距离约5,000光年远的三叶星云，与右下角的疏散星团M21分享了这片取景佳妙的视野，构成了探索天体对比的多彩案例。受到尘埃带分割的三叶星云，大小约为40光年，年龄则在30万年左右。因此，它是我们天空中最年轻的恒星形成区之一，其内的新生恒星和胎星仍然包裹在孕育它们的尘埃和云气里。而估计距离和M20相当的疏散星团M21，内部的恒星之年龄是远为年长的8百万年。虽然它们分享了这片壮丽的望远镜星野，不过，它们二者之间并无明显的关联。{lamp/}原文：{mtitle title="Messier 20 and 21"/}Image Credit &Copyright:IgnacioDiaz BobilloExplanation: The beautiful Trifid Nebula,also known as Messier 20, is easytofind with a small telescope in the nebula rich constellation Sagittarius.About 5,000 light-years away, the colorful study incosmic contrasts sharesthiswell-composed, nearly 1 degree wide field withopen star clusterMessier 21(bottom right).Trisected by dust lanesthe Trifid itself is about 40 light-years across anda mere 300,000 years old.That makes it one of theyoungest starformingregions in our sky,with newborn and embryonic stars embedded in itsnatal dust and gas clouds.Estimates of the distance to open star cluster M21 are similar to M20's,but though they share this gorgeous telescopic skyscapethere is no apparent connection between the two.In fact, M21's stars are much older, about 8 millionyearsold.

2017年06月28日:梅西叶20与21的组合影像-（Composite Messier 20 and 21） 2017年06月28日:梅西叶20与21的组合影像-（Composite Messier 20 and 21）--原图下载{mtitle title="梅西叶20与21的组合影像"/}Image Credit &Copyright: Martin Pugh说明: 距离约5,000光年远、亦名为M20的美丽三叶星云，是一个探索天体对比的多彩案例。在这张跨幅1度的影像里，它与左上角的疏散星团M21分享了这片视野。受到尘埃带分割的三叶星云，大小约为40光年，年龄则在30万年左右。因此，它是我们天空中最年轻的恒星形成区之一，其内部的新生恒星和胎星仍然包裹在孕育它们的尘埃和云气里。而疏散星团M21内的恒星之年龄是远为年长的8百万年；虽然它的估计距离也和M20相当，更分享这片壮丽的望远镜星野，不过它们之间并无明显的关联。M20和M21都是用小望远镜，就可以轻易在满布星云的人马座之内找到的天体。这幅使用2部不同的望远镜所拍摄的影像，则组合了高分辨率的窄波段M20照片和另一张涵盖M21的较大视野照片。{lamp/}原文：{mtitle title="Composite Messier 20 and 21"/}Image Credit &Copyright: Martin PughExplanation: The beautiful Trifid Nebula,also known as Messier 20, lies about 5,000 light-years away, acolorful study in cosmic contrasts.It shares this nearly 1 degree wide field withopen star clusterMessier 21(top left).Trisected by dust lanesthe Trifid itself is about 40 light-years across anda mere 300,000 years old.That makes it one of theyoungest starforming regions in our sky, with newborn and embryonic stars embeddedin its natal dust and gas clouds.Estimates of the distance to open star cluster M21 are similar to M20's,but though they share this gorgeous telescopic skyscapethere is no apparent connection between the two.M21's stars are much older, about 8 millionyearsold.M20 and M21 are easytofind with even a small telescope in the nebula rich constellationSagittarius.In fact, this well-composed scene is acomposite from two different telescopes.Using narrowband data it blends a high resolution image of M20 with awider field image extending to M21.

2014年08月28日:梅西叶20与21-（Messier 20 and 21） 2014年08月28日:梅西叶20与21-（Messier 20 and 21）--原图下载{mtitle title="梅西叶20与21"/}Image Credit &Copyright:Lorand Fenyes说明: 美丽的三裂星云 (Trifid Nebula)又名为M20，是个用小型望远镜，就可以在满布星云的半人马座内轻易找到之天体。在这张取景佳妙、跨幅将近1度的广角影像里，距离约5,000光年远的三裂星云与右上角的疏散星团M21，在色彩上形成鲜明的对比。受到尘埃带分割的三裂星云，大小约为40光年，年龄则在30万年左右。因此，它是我们天空中最年轻的恒星形成区之一，其内部的新生恒星和胎星，还包裹在孕育它们的尘埃和云气里。疏散星团M21的估计距离和M20相当，然而，虽然它们分享这片壮丽的望远镜星野，但它们之间并无明显的关联。事实上，M21的恒星年龄是远为年长的8百万年。{lamp/}原文：{mtitle title="Messier 20 and 21"/}Image Credit &Copyright:Lorand FenyesExplanation: The beautiful Trifid Nebula,also known as Messier 20, is easytofind with a small telescope in the nebula rich constellationSagittarius.About 5,000 light-years away, the colorful study incosmic contrasts sharesthiswell-composed, nearly 1 degree wide field withopen star clusterMessier 21(top right).Trisected by dust lanesthe Trifid itself is about 40 light-years across anda mere 300,000 years old.That makes it one of theyoungest star formingregions in our sky,with newborn and embryonic stars embedded in itsnatal dust and gas clouds.Estimates of the distance to open star cluster M21 are similar to M20's,but though they share this gorgeous telescopic skyscapethere is no apparent connection between the two.In fact, M21's stars are much older, about 8 millionyears old.