Ross 508 is a cool M-dwarf (about 0.18 solar masses, 3,071 K, 0.21 solar radii), 11.2 light-years from Earth. Ross 508 b is a 4.0-Earth-mass planet, with an orbital period of 10.8 days, at 0.054 AU from its star, on an eccentric orbit (e ≈ 0.33), discovered in 2022 via radial velocity. The planet betrayed itself through the star's reflex motion — a technique that first revealed worlds around Sun-like stars in the 1990s and remains a workhorse of exoplanet discovery. The planet's marked eccentricity suggests past scattering events or perturbations from unseen companions.