An anti-tail (or antitail), is an apparent spike extending from the coma of a comet towards the Sun, and therefore in the opposite direction to the other comet tails: the ion tail and the dust tail. The anti-tail consists of larger dust particles left behind by the comet. These dust particles are less affected by the Sun's radiation pressure and tend to remain roughly in the comet's orbital plane and eventually form a disc along the comet's orbit due to the ejection speed of the particles from the comet's surface. As Earth passes through the comet's orbital plane, this disc is seen side on, and appears as the characteristic spike. [1] The other side of the disc can sometimes be seen, though it tends to be lost in the dust tail. The anti-tail is therefore normally visible for a brief interval only when Earth passes through the comet's orbital plane. [2] [3]
Most comets do not develop sufficiently for an anti-tail to become visible, but notable comets that did display anti-tails include Comet Arend–Roland in 1957, [4] Comet Kohoutek in 1973, [5] Comet Hale–Bopp in 1997, C/1999 H1 (Lee) [6] in 1999, Comet Lulin in 2009, Comet PANSTARRS in 2013, C/2022 E3 (ZTF) in 2023, [7] 12P/Pons–Brooks [8] in 2024 and C/2023 A3 Tsuchinshan–ATLAS [9] in 2024.
