Astronomy Picture of the Day——星像迹线与春分日出
Discover the cosmos! Each day a differentimage or photograph of our fascinating universe is featured, along with a briefexplanation written by a professional astronomer.
Star Trails and the Equinox Sunrise
Image Credit & Copyright: Juan CarlosCasado (TWAN, Earth and Stars)
Acknowledgement: Andrea Rodriguez Anton
Explanation: Stars trail and the Sun risesin this night and day composite panorama made on March 19. The view lookstoward the eastern horizon from La Nava de Santiago, Spain. To create it, acontinuous series of digital frames was recorded for about two hours andcombined to trace the concentric motion of the stars through the night sky. Areflection of the Earth's rotation, star trails curve around the northcelestial pole toward upper left and the south celestial pole toward the lowerright. Of course on that day the Sun was near the celestial equator, a diagonalstraight line in the wide-angle projection. A dense dimming filter was used tocapture the Sun's image every two minutes. Superimposed on the star trails itrose due east in the morning sky. In the scene, foreground landscape and alocal prehistoric monument were illuminated by full moonlight, though. Themonument's corridor faces nearly to the east and the equinox sunrise.
星像迹线与春分日出
说明：这幅全景照片拍摄于今年3月19日，它呈现了星像迹线与日出。图中展示的是从西班牙的拉纳瓦德圣地亚哥朝向东方地平线眺望的景象。为了合成这幅照片，摄影师花费了大约两个小时持续记录，组合起来后追踪到了恒星在夜空中以同心圆形式运动。作为地球自转的映射，星像迹线向左上方的北天极和右下方的南天极弯曲。因为那天太阳位于天赤道附近，所以在广角投影是一条对角线。利用一台调光滤波器每两分钟捕捉一次太阳影像，并将它叠加在星像迹线上，太阳在黎明天空的正东方升起。然而，在这幅图片中，前景的当地一座史前纪念碑被月光照亮。纪念碑的走廊几近面向正东和春分日出。
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