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Why can a comet appear to have an antitail pointing toward the Sun?
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Comet
Comet McNaught with filamentary tail and the Moon over the Pacific Ocean, photographed from Paranal Observatory, Chile, January 2007.
An antitail is not a physical structure pointing toward the Sun, but rather an optical illusion caused by a projection effect.12
While a comet typically develops a Type II tail consisting of dust particles blown away from the Sun by radiation pressure, this debris is actually scattered behind the comet along its orbital path. When Earth passes through the comet’s orbital plane, our line of sight aligns with this fan of debris. From this perspective, the dust trail appears to extend toward the Sun, creating the visual appearance of a spike or "antitail".12