Orbital Period of a Comet
Given the minimum and maximum distance of the orbit of a comet in an elliptical orbit, you can use Kepler’s Third Law and the definition of the semi-major axis of an ellipse to calculate its orbital period
P is the orbital period of the comet,
is the mathematical constant pi,
a is the semi-major axis of the comet’s orbit,
G is the gravitational constant,
M is the mass of the Sun, and
m is the mass of the comet.