Astronomers have spotted the biggest comet ever! And it's heading for Earth! Except (a) it's not heading towards Earth — it's closest approach to us will be beyond Saturn's orbit — and (b) it's not technically the biggest. But it's still cool! Emily's here with loads of info about comets, big comets, things that are sort of comets, how many tails they have (hint: it's more than one), and heaps more besides.