Final answer:
Cometary orbits usually have very large eccentricities, often approaching (or even exceeding) unity. Comets spend most of their time far from the Sun, moving very slowly. As they approach perihelion, the comets speed up and whip through the inner parts of their orbits more rapidly.
Step-by-step explanation:
Cometary orbits typically have very large eccentricities, often approaching or even exceeding unity. Eccentricity is a measure of how elongated an orbit is, with a value of 1 representing a perfectly parabolic orbit. Comets, such as Halley's Comet, have orbits with eccentricities greater than 0.8.
According to Kepler's second law of planetary motion, comets spend most of their time far from the Sun, moving very slowly. As they approach perihelion (the point in their orbit closest to the Sun), they speed up and move through the inner parts of their orbits more rapidly.