Size comparison of three exoplanets orbiting the M Dwarf star L 98-59, illustration. Exoplanets are planets that orbit stars other than the Sun. The L98-59 exoplanets were discovered by NASA's Transiting Exoplanet Survey Satellite (TESS), which measures the dip in star light as planets pass between the host star and TESS. L 98-59b is around 0.8 times Earth's size and L 98-59c and L 98-59d are respectively around 1.4 and 1.6 times Earth's size. The exoplanets lie too close to their host star for liquid water to exist and are thus considered to be outside the habitable zone.