Pronunciation: [ɐpˈə͡ʊpsɪs] (IPA) 
The word "apoapsis" refers to the point in an object's orbit that is farthest away from the center of mass, usually in reference to celestial bodies. The word is spelled "a-p-o-a-p-s-i-s" with the emphasis on the first syllable "a". It can be pronounced as /æpəʊˈæpsɪs/ (uh-poh-ap-sis) with the first syllable sounding like "uh" and the "o" being pronounced like "oh". The "s" sound in the second syllable is pronounced like "z".
Apoapsis, often referred to as apogee, is a term used in astronomy and physics to describe a point in an object's orbit that is farthest from the celestial body it is orbiting around. It is a significant concept in celestial mechanics, particularly for objects like planets, moons, satellites, and spacecraft that revolve around other celestial bodies.
Consider an object, such as a satellite, orbiting the Earth. The highest point of its orbit, where it is farthest from the Earth's surface, is called the apoapsis. At this point, the object's orbital velocity is at its minimum, resulting in a slower movement compared to other parts of the orbit. The opposite of apoapsis is the periapsis, also known as perigee, which is the point in the orbit where the object is closest to the celestial body it is orbiting.
The term "apoapsis" is derived from the Greek words "apo" meaning "away from" and "apsis" meaning "arch" or "curve." It is used to describe the farthest point an object reaches in its elliptical or circular orbit. The distance between the apoapsis and periapsis determines the eccentricity of the orbit, with a larger separation indicating a more elongated orbit.
Understanding the apoapsis is crucial in analyzing and predicting an object's orbit around a celestial body. It allows scientists, astronomers, and engineers to calculate various parameters, such as orbital periods and velocities, and provides valuable insights into the mechanics of celestial dynamics and gravitational interactions.
The word "apoapsis" is derived from two Greek terms: "apo" (ἀπό), meaning "away from", and "apsis" (ἁψίς), meaning "arch" or "loop". In astronomy, apoapsis refers to the point in an orbit that is farthest from the body being orbited. It is often used in relation to celestial bodies orbiting around a larger object, such as a planet orbiting a star.
