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.
