星系与南天极
Galaxies and the South Celestial Pole
Image Credit & Copyright: Petr Horalek, Josef Kujal
Explanation: The South Celestial Pole is easy to spot in star trail images of the southern sky. The extension of Earth’s axis of rotation to the south, it’s at the center of all the southern star trail arcs. In this starry panorama streching about 60 degrees across deep southern skies the South Celestial Pole is somewhere near the middle though, flanked by bright galaxies and southern celestial gems. Across the top of the frame are the stars and nebulae along the plane of our own Milky Way Galaxy. Gamma Crucis, a yellowish giant star heads the Southern Cross near top center, with the dark expanse of the Coalsack nebula tucked under the cross arm on the left. Eta Carinae and the reddish glow of the Great Carina Nebula shine along the galactic plane near the right edge. At the bottom are the Large and Small Magellanic clouds, external galaxies in their own right and satellites of the mighty Milky Way. A line from Gamma Crucis through the blue star at the bottom of the southern cross, Alpha Crucis, points toward the South Celestial Pole, but where exactly is it? Just look for south pole star Sigma Octantis. Analog to Polaris the north pole star, Sigma Octantis is little over one degree fom the the South Celestial pole.
Tomorrow’s picture: apollo’s muse
星系与南天极
影像提供与版权: Petr Horalek, Josef Kujal
说明: 在记录恒星迹线的影像里，南天极轻易可辨。因为地球自转轴的指向，就位在所有南天恒星迹线弧的中心。在这张跨幅约60度的南极深空全景影像里，南天极则位在中心附近，四周环拱着明亮的星系和南天的天空珍宝。在影像的顶缘附近，可见到我们银河盘面上的恒星和星云。南十字座顶端的泛黄巨星十字架一，位在影像的顶缘中心，而广袤的煤袋星云则位在十字架横臂的左下方。银河盘面右缘附近，可见海山二与散发泛红辉光的船底大星云。影像的下缘附近有大与小麦哲伦星系，它们除了是河外星系之外，也是我们庞大银河系的伴星系。南十字座的十字架一及下方泛蓝十字架二所构成的直线，指向南天极，不过它到底位在何处呢？就在南天的指极星─南极座σ附近。类似北天的北极星，南极座σ与南天极的间距超过1度。
明日的图片: apollo’s muse
