How can it fly backwards? Or, rather, how can anyone determine that it is flying forward or backward?
They mention that it is flying in the opposite direction around the solar system as most comets. Maybe that’s what they mean by backwards?
Imagine a steam engined boat with steam coming out of the top of a smoke stack. When the boat is travelling in still air the steam lags behind the boat. If a picture was taken of it you could guess it’s direction of movement based on the tail.
Thats not the case with a comet because theres no air to cause the drag and slow down the tail. Instead the direction of the tail is based on the direction of the solar wind.
So if a comet is heading towards the sun it is said to have a backwards tail or flying backwards.