Comet Hale-Bopp. This was one of the brightest comets of the 20th Century. It was visible during the first half of 1997. The comet has two clear tails; a white dust tail and a blue ion tail. The dust tail is formed of dust particles blown off the comet by sunlight. The ion tail is made up of glowing ionised gas pushed off the comet by the charged solar wind. Both tails always point away from the Sun.