Astronomy Picture of the Day——人马座内的星云
Deep Field: Nebulae of Sagittarius
Image Credit & Copyright: Emilio RiveroPadilla
Explanation: These three bright nebulae areoften featured on telescopic tours of the constellation Sagittarius and thecrowded starfields of the central Milky Way. In fact, 18th century cosmictourist Charles Messier cataloged two of them; M8, the large nebula just leftof center, and colorful M20 on the top left. The third emission region includesNGC 6559 and can be found to the right of M8. All three are stellar nurseriesabout five thousand light-years or so distant. Over a hundred light-yearsacross, the expansive M8 is also known as the Lagoon Nebula. M20's popular monikeris the Trifid. Glowing hydrogen gas creates the dominant red color of theemission nebulae. In striking contrast, blue hues in the Trifid are due to dustreflected starlight. Recently formed bright blue stars are visible nearby. Thecolorful composite skyscape was recorded in 2018 in Teide National Park in theCanary Islands, Spain.
人马座内的星云
这三个明亮的星云经常出现在望远镜影像下的人马座和中央银河系密集的星场中。实际上，宇宙观测者查尔斯·梅西耶在18世纪就已经对其中的两个星云进行了编录：位于影像中央偏左的庞大星云M8，位于图像左上方的彩色星云M20。在M8的右侧是包含NGC 6559星云的第三个发光去。这三片星云都是恒星的孕育基地，距离我们约5000光年或者更远。广阔星云M8的跨度超过一百光年，它更广为人知的名字是礁湖星云。M20更通俗的名称是三裂星云。炽热氢气发出了发光去区所呈现的红色。与之形成鲜明对比的是，三裂星云因尘埃反射的星光呈现出蓝色光泽。在附近能看到形成不久的蓝色恒星。这幅多彩的天空影像是2018年在西班牙加那利群岛的泰德国家公园拍摄的。
参考文献：
https://apod.nasa.gov/apod/image/1905/M8M20_Padilla_1534.jpg
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Astronomy Picture of the Day——太阳系的行星：倾斜与自转