🔍 Key Concepts

• Earth’s orbit around the Sun is not a perfect circle • Meaning of the prefixes peri- and ap- (apo-) in astronomy • Difference between Earth–Sun distance and Earth–Moon–Sun lineups (eclipses, syzygy)

💭 Think About

• Think about what peri- usually means in words like perigee and periapsis: does it refer to the closest point or the farthest point in an orbit? • Which choices talk about distance between Earth and Sun, and which talk about alignment of the Earth, Moon, and Sun? • For options mentioning the Moon, ask: does the definition of perihelion actually depend on the Moon at all?

✅ Before You Answer

• Identify which options describe distance in an orbit versus positional alignment of three bodies • Recall: helio- refers to the Sun; compare this to geo- (Earth) and how perigee is defined • Eliminate any choice that requires the Moon, since perihelion is defined only by the Earth–Sun relationship