This is NOT a comet, not even a meteor, but the planet Mercury, which can currently be found very close to the Pleiades at dusk. How is the tail formed? The solar wind and micro-meteorites eject sodium atoms from Mercury's surface. This creates a yellow-orange tail of sodium gas that is around 2.5 million kilometers long. This shot was only possible under best viewing conditions and in combination with a special 589nm filter. #space