Exoplanet Detection Methods, Diversity, and the Search for Habitable Worlds

Abstract

 An exoplanet is a planet which is orbiting a star other than the Sun. Exoplanet research has grown quickly since the first exoplanet was discovered around a star like the Sun in 1995. In the NASA Exoplanet Archive, as of 15 October 2026, there were 6,451 exoplanets confirmed, with over 1,000 of those being found by the Transiting Exoplanet Survey Satellite (TESS). This review discusses the main approaches employed to discover these worlds and illustrates how various techniques are involved in the discovery and study of these worlds. It also explores planetary diversity, understanding of planetary atmosphere and the concept of the habitable zone, which plays a crucial role in the discussion of potentially life-sustaining planetary environments. These topics together give a picture of what an exoplanet is, and how it can be judged for its potential habitability. The review also concludes that future space missions and better spectroscopic observations will be needed to explore planetary atmosphere, create a more complete picture of distant worlds and evaluate the potential of some exoplanets for being habitable, a view they acknowledge is limited by existing evidence.