What is the definition of apogee in astronomy?

Apogee is defined as the point in the orbit of a celestial body where it is farthest from Earth. This term is particularly relevant in the context of orbits, such as those of satellites or the Moon around Earth. When a satellite reaches apogee, it experiences the lowest gravitational pull from Earth, which affects its speed and the time it takes to complete an orbit. Understanding apogee is crucial in satellite mission planning and space exploration because it influences the performance and operational aspects of satellites, including their communication and observational capabilities.

The other options define different points in astronomical terms: the point closest to the sun refers to perihelion, the point closest to Earth is perigee, and the position of Earth relative to the sun at its closest approach is also perihelion. Thus, these terms emphasize different distances relevant to various celestial bodies and their orbits, distinct from what apogee describes.