In orbital astronomy, what is the term for the point in a planet's elliptical orbit where it is at the maximum distance from the Sun?

Introduction / Context:
Planets and many other bodies move around the Sun in elliptical orbits, not perfect circles. In such orbits, the distance between the planet and the Sun changes over the course of one revolution. These closest and farthest points have specific names in astronomy, which are frequently tested in general science and geography exams. This question asks you to identify the term used for the point where a planet is at its maximum distance from the Sun.

Given Data / Assumptions:
- The question clearly refers to a planet in its orbit around the Sun.
- It asks for the term meaning maximum distance from the Sun.
- The options include perihelion, aphelion, apogee, and perigee.
- We assume standard astronomical terminology for orbits around the Sun and around the Earth.

Concept / Approach:
For bodies orbiting the Sun, the terms perihelion and aphelion are used. Perihelion is derived from “peri,” meaning near, and “helion,” referring to the Sun, so it is the point where the planet is closest to the Sun. Aphelion (sometimes written as aphelion) is derived from “ap,” meaning away, and “helion,” so it denotes the point where the planet is farthest from the Sun. For bodies orbiting the Earth, such as moons or artificial satellites, the terms perigee (closest to Earth) and apogee (farthest from Earth) are used. Since the question is specifically about a planet's maximum distance from the Sun, the correct term is aphelion.

Step-by-Step Solution:
Step 1: Identify that the orbit described is around the Sun, not around the Earth. Step 2: Recall that perihelion refers to the point of closest approach to the Sun, so it cannot be the maximum distance. Step 3: Remember that aphelion refers to the point of greatest distance from the Sun in a heliocentric orbit. Step 4: Recognise that apogee and perigee are terms used for distance from the Earth, not the Sun. Step 5: Select aphelion as the correct term for maximum distance from the Sun.

Verification / Alternative check:
Astronomy references define aphelion as the point in the orbit of a planet or other body where it is farthest from the Sun. Many almanacs list the dates when Earth reaches perihelion and aphelion each year. Diagrams of orbits label the nearer point as perihelion and the farther point as aphelion. Similarly, they use apogee and perigee only for orbits around Earth. These consistent descriptions confirm that aphelion is the correct answer for a planet's maximum distance from the Sun.

Why Other Options Are Wrong:
Perihelion, the point of minimum distance from the Sun, is the opposite of what the question asks for.
Apogee, the point of maximum distance from the Earth, applies to Earth satellites and the Moon, not to planets orbiting the Sun.
Perigee, the point of minimum distance from the Earth, again refers to Earth centred orbits and is not relevant to the Sun planet distance in this question.

Common Pitfalls:
Students sometimes mix up perihelion and aphelion because both end with “helion.” A useful way to remember is that “peri” sounds like “pair” or “near,” suggesting closeness, while “ap” in aphelion suggests “apart” or “away.” Similarly, apogee and perigee are reserved for Earth orbits, so whenever the Sun is mentioned, think of perihelion and aphelion, not perigee or apogee. Keeping these prefixes straight will help you answer orbital terminology questions quickly and accurately.

Final Answer:
The point of maximum distance from the Sun in a planet's orbit is called Aphelion, the point of maximum distance from the Sun.