2025年7月4日
NGC 6946 and NGC 6939
Image Credit & Copyright: Alberto Pisabarro
Explanation: Face-on spiral galaxy NGC 6946 and open star cluster NGC 6939 share this cosmic snapshot, composed with over 68 hours of image data captured with a small telescope on planet Earth. The field of view spans spans about 1 degree or 2 full moons on the sky toward the northern constellation Cepheus. Seen through faint interstellar dust couds near the plane of our Milky Way galaxy, the stars of open cluster NGC 6939 are 5,600 light-years in the distance, near bottom right in the frame. Face-on spiral galaxy NGC 6946 is at top left, but lies some 22 million light-years away. In the last 100 years, 10 supernovae have been discovered in NGC 6946, the latest one seen in 2017. By comparison, the average rate of supernovae in our Milky Way is about 1 every 100 years or so. Of course, NGC 6946 is also known as The Fireworks Galaxy.
Tomorrow’s picture: squid game
NGC 6946与NGC 6939
影像提供与版权: Alberto Pisabarro
说明: 在组合自地面小望远镜超过68小时长曝光数据的这幅宇宙影像里，正向螺旋星系NGC 6946与疏散星团NGC 6939，共享了这片视野。这片宽约1度（2个满月宽度）、远眺北天的仙王座方向的视野，视线穿透银河系中央盘面附近暗淡的星际尘埃云。视野右下角的疏散星团NGC 6939，距离约为5,600光年，而左上角的正向螺旋星系NGC 6946，与我们相距约2千2百万光年。于过去的1百年之中，在NGC 6946内已经发现了10颗超新星。例如在不久前的2017年，星系NGC 6946就曾有超新星闪现。相较之下，我们银河系大约每百年左右会出现一颗超新星。也因此，NGC 6946有烟火星系之称。
明日的图片: squid game
