The first planet ever found orbiting another star was detected in 1995, and it belonged to a class now known as a “hot Jupiter.” These exoplanets are comparable in mass to Jupiter but circle their stars in just a few days. Scientists now believe that hot Jupiters originally formed far from their stars, similar to Jupiter in our Solar System, and later moved inward.

Two main processes have been proposed to explain this journey: high-eccentricity migration, where gravitational interactions with other objects distort a planet’s orbit before tidal forces near the star gradually make it circular; and disk migration, in which a planet slowly spirals inward while embedded in the protoplanetary disk of gas and dust.