tau Gem is an orange K-type dwarf (about 2.30 solar masses, 4,388 K, 26.8 solar radii), 113 light-years from Earth. tau Gem b is a 20.6-Jupiter-mass companion, with an orbital period of 306 days, at 1.170 AU from its star, discovered in 2013 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. tau Gem b orbits at roughly the distance of Mars from the Sun.