During the 18th century, French astronomer Charles Messier compiled a list of over 100 cosmic objects that might fool fellow comet hunters into thinking they had discovered new comets. In the 1980s, an Englishman named Sir Patrick Moore produced an additional list to highlight more cosmic wonders visible to amateur astronomers. Unlike the Messier catalog, which only features objects that were visible from Charles Messier’s viewing location in Europe, Moore’s Caldwell catalog includes celestial bodies that are found in both the northern and southern skies. The catalog consists of 46 star clusters, 35 galaxies and 28 nebulas. Moore intentionally avoided including any of the Messier objects in his catalog, hoping to expand his fellow amateur astronomers’ cosmic horizons. From nearby clouds of gas and dust that are left over from dying stars to remote galaxies that formed billions of years ago, the Caldwell catalog is brimming with surprising celestial treats.
This loose collections of stars, known as an open star cluster, is image 100 of the catalog. Caldwell 100 (also called Collinder 249) is an open star cluster that’s embedded within a large nebula (named IC 2944) about 6,000 light-years away from Earth. The reddish glow of hydrogen gas surrounding the cluster is typical of emission nebulas found in massive star-forming regions. This Hubble image, taken in visible light using the Wide Field and Planetary Camera 2, shows a small portion of this region.
在18世纪，法国天文学家查尔斯·梅西耶（Charles Messier）编制了一份清单，列出了100多种宇宙物体，这些物体可能会欺骗其他彗星猎人以为他们发现了新彗星。在1980年代，一位名叫帕特里克·摩尔爵士（Sir Patrick Moore）的英国人制作了一个附加清单，以突出业余天文学家可以看到的更多宇宙奇观。不同于梅西耶目录（该目录仅包含从查尔斯·梅西耶在欧洲的观看位置可见的物体），摩尔的考德威尔（Caldwell）目录中包括在北部和南部天空中都可以找到的天体。该目录由46个星团，35个星系和28个星云组成。摩尔有意避免将任何梅西耶对象包括在他的目录中，以扩大他的业余天文学家的宇宙视野。从垂死的恒星遗留下来的附近的气体和尘埃云到数十亿年前形成的遥远星系，考德威尔目录充满了令人惊讶的天体。
影像来源：NASA and the Hubble Heritage Team (STScI/AURA); 致谢: Bo Reipurth (University of Hawaii)