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北极星和ZTF彗星的轨迹

(原标题: Polaris and the Trail of Comet ZTF)

2023-02-03

浏览次数: 16

1月31日,在西班牙莱伊达Àger附近,用固定在三脚架上的数码相机拍摄了这张三小时长的夜空合成图,照片中恒星围绕着北天极形成同心弧线。在那一天,彗星C/2022 E3 (ZTF)接近地球天空中最北的赤纬。这使得彗星距离地球的北天极大约10度,使得彗星的位置总是在地平线之上,从地球上所有超过北纬10度的地方来看。在星迹图中,地球自转轴向太空的延伸在左边。北极星沿着距离北天极不到一度的短而明亮的同心弧线运行。右图显示了ZTF彗星的轨迹,它的表观运动主要反映了地球像恒星一样的自转。但在2月1日接近地球的时候,这颗彗星相对于背景恒星的移动也很明显。当ZTF彗星扫过长颈骆驼座时,它弥漫的绿色轨迹几乎是一条与星迹混合在一起的同心弧线。

查看原文解释

Stars trace concentric arcs around the North Celestial Pole in this three hour long night sky composite, recorded with a digital camera fixed to a tripod on January 31, near Àger, Lleida, Spain. On that date Comet C/2022 E3 (ZTF) was near its northernmost declination in planet Earth's sky. That put the comet about 10 degrees from Earth's North Celestial Pole making the comet's position circumpolar, always above the horizon, from all locations on planet Earth at more than 10 degrees northern latitude. In the startrail image, the extension of Earth's axis of rotation into space is at the left. North star Polaris traces the short, bright, concentric arc less than a degree from the North Celestial Pole. The trail of Comet ZTF is indicated at the right, its apparent motion mostly reflecting Earth's rotation like the stars. But heading for its closest approach to planet Earth on February 1, the comet is also moving significantly with respect to the background stars. The diffuse greenish trail of Comet ZTF is an almost concentric arc mingled with startrails as it sweeps through the long-necked constellation Camelopardalis.

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