What term describes the farthest or highest point of an orbit?

The term that describes the farthest point of an orbit is "apogee." This term specifically refers to the point in an orbit around the Earth where the satellite is at its maximum distance from the planet. Understanding this concept is crucial in orbital mechanics, as it helps in calculating the dynamics and positioning of various spacecraft and satellites.

Periapsis, in contrast, is the term used for the closest point in an orbit to the body being orbited, which is the opposite of apogee. Zenith typically refers to the highest point in the sky relative to an observer on the surface of the Earth and is not a term used in the context of orbits. Perigee refers to the closest point in an orbit around the Earth, similar to periapsis, but is specific to Earth-related orbits. Therefore, apogee is the appropriate term for the farthest point in an orbit.