What formula would be used to calculate the aphelion distance of Halley's Comet from the sun? Halley’s comet has a perihelion distance of 0.6 AU & an orbital period of 76 years,
Given the aphelion distance and period given the perihelion distance is 35.28AU.
Kepler's third law relates the orbit period T in years to the semi-major axis distance a in AU using the equation
Given that the comet's orbit is an ellipse then the sum of the perihelion distance and the aphelion distance is twice the semi-major axis
A direct equation relating the three values would be: