Since the early 1990s when the first this wonderful Caltech Exoplanet Archive page! But, what is an exoplanet, and how do we know exoplanets exist?
What is an exoplanet?
Planet, a term coined by ancient Greeks, describes a celestial body moving in an elliptical orbit around a star.” (Dictionary.com). Simply put, an exoplanet is any given planet that orbits (revolves around) a star outside of our solar system.
Big, fast, hot, cold, tiny, if a body meets necessary criteria to be an official planet, and it is not within the grasp of our Sun’s mighty gravity, it can be an exoplanet.
Then, how do we know exoplanets exist?
But, the nearest star system to our Sun is Alpha Centauri, a triple star system 4.2