Hale–Bopp was active at the large heliocentric distances of 21.6 and 27.2 AU.

The structure of the tail changed significantly in 3.3 years between observations.

Commonly used dynamical models cannot explain the shape of the tail.

The Lorentz force likely plays a major role in the motion of the dust in the tail.

The tail is likely made of 尾 = 0.3 particles, with radii of ∼0.5–5 渭m.