The explosive, green"devil comet" that recently swept close to Earth appeared to grow an impossible second tail as it passed us, new photos reveal. But this extra limb, known as an anti-tail, is actually an extremely rare optical illusion caused by the comet's proximity to our planet.
During the comet's initial eruptions last year, its expanded coma grew, giving the impression that it had grown a pair of demonic horns, which earned it its sinister nickname. But these horns did not appear in subsequent eruptions. Related: Explosive, green 'devil comet' has hidden spiral swirling around its icy heart, photo trickery reveals
However, the comet had not actually grown another tail. Instead, we are seeing light reflecting off the gas and dust left behind in the comet's wake. Normally, this is invisible to us. But when Earth passes through the comet's orbital plane, as it did on June 3, this trail of debris is illuminated by the sun, according to Spaceweather.com.