The term extrasolar planet or exoplanet can apply to any world revolving round another star.
However, until quite recently – 1995 – none had actually been detected. The first was 51 Pegasi b, and more followed quite rapidly. Most were discovered using Doppler spectroscopy: shifts toward blue or red in the light of the star. The first claims of direct observation came in 2004. Hardy was one of the first artists chosen to depict how these may look.