A protuberance from a comet that appears to point towards the Sun, often looking like a spike. It is actually part of the comet’s dust tail, and consists of larger (millimetre-sized) particles lagging behind the comet in its orbit. The antitail does not actually point sunwards, but results from a perspective effect when the comet is seen from a certain angle. Antitails are uncommon. Where present, they are usually most prominent when the Earth passes through, or close to, the plane of the comet’s orbit. The cometary dust, which lies in a thin sheet, is then seen edge-on.