At which point,as seen from Earth,will a planet appear exactly half-lit (looking like the first quarter or last quarter Moon)? (It may help to draw a diagram and show the sunlit side of the planet on it.)

Question

Quizplus · Accepted Answer

At greatest elongation, the planet is at its maximum angular distance from the Sun as seen from Earth, making it appear half-lit, similar to the first or last quarter Moon.

At Which Point,as Seen from Earth,will a Planet Appear Exactly