Question

Halley’s comet has a perihelion distance of 0.6 au and an orbital period of 76 years. what is its aphelion distance from the sun?

Answer 1

Aphelios derived from the Greek word, “apo” means far and “helios” meaning sun, it means far away from the sun.
To solve:
The Period gives the semi-major axis of the orbit:

a3 = P2 a = P2/3 = (76 AU)2/3 = 17.9 AU
so…
ra + rp = 2a ra = 2a - rp = 2(17.9) - 0.6 = 35.2 AU

Therefore, Halley's Comet stretches maximum distance from the Sun between the orbits of the planets, Neptune and Pluto.