Seen here on June 13th from southern New Mexico, this Comet McNaught's long ion tail sweeps across the telescopic field of view (a negative image is inset).

这是6月13日新墨西哥南部所见，麦克·诺特的长离子尾扫过望远镜的视野，插图是负片。

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The red circle is the orbit of a long period object like a comet. Note the object and its tail.

红色的圈是一个类似彗星的长周期天体的轨道，注意一下这个天体和它的尾巴。

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The tail lengths of comet were used to measure DNA damage.

以彗星尾长作为DNA损伤程度的评价指标。

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"When they come close to the Sun, this ice melts - solar wind blows this material out into space, so you get a tail of matter coming off the comet, " explains O'Brien.

BBC: Star of Bethlehem: The astronomical explanations

His figures were roughly a centimetre tall, most made with two deliberate strokes of the brush, and allowed to fade away as his paint ran out, like the trailing tail of a comet.

ECONOMIST: Roman Opalka