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How did Comet Arend-Roland’s apparent antitail form?
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Comet
Comet McNaught with filamentary tail and the Moon over the Pacific Ocean, photographed from Paranal Observatory, Chile, January 2007.
The apparent antitail of Comet Arend-Roland was not a physical tail pointing toward the Sun, but rather an optical illusion caused by perspective.1
While the comet possessed a dust tail (or Type II tail) consisting of debris scattered along its orbit, the antitail appeared when Earth passed through the comet’s orbital plane. From this specific vantage point, observers were viewing a fan-shaped distribution of debris edgewise. This perspective caused the dust trail, which was actually curving behind the nucleus, to appear as a sharp, narrow spike projecting toward the Sun.12