Comets also have their troubles, their perihilions, their hyperbolas and their parabolas.
A few cometary orbits are hyperbolas, more ellipses, and a still greater number parabolas.
If, in this approach, they are not disturbed by any of the large planets, they again recede in parabolas or hyperbolas.
It is easily seen that the curves traced by the shadow of the point P are hyperbolas whose convexity is turned toward A B.
They move in very eccentric orbits—some, perhaps, in parabolas or hyperbolas.