What defines an exoplanet?

An exoplanet is defined as a planet that exists outside of our solar system, orbiting stars other than the Sun. This definition is crucial because it distinguishes exoplanets from those within our own solar system. The study of exoplanets has gained significant attention in astronomy, particularly with advancements in telescope technology and detection methods, enabling scientists to discover thousands of these distant worlds.

The term specifically refers to any planetary body that resides in the space between stars, highlighting the diversity and potential characteristics of planets that may exist in various environments across the universe. Understanding exoplanets helps researchers learn more about planetary formation, the possibility of life beyond Earth, and the various conditions that contribute to the development of planetary systems.

The other options do not meet the criteria for an exoplanet. A planet within our solar system refers to the eight recognized planets, such as Earth and Mars, and would not be classified as an exoplanet. The idea of a theoretical planet in another galaxy does not pertain to our current understanding or classification system of exoplanets, as they must be observed and proven to exist. Lastly, a moon orbiting a gas giant is not considered an exoplanet because it is a natural satellite of a planet within a solar system