A charming double star, composed of blue-white components with magnitudes 4.7 and 4.8, separated by 7.8", which can be resolved with a 5 cm telescope. Mesarthim is visible to the naked eye as a star with magnitude 3.9. Historically, it is interesting because it was one of the first double stars discovered by a telescope, observed by the English naturalist Robert Hooke in 1664 while observing a comet. It is located 204 light-years away.