John Monroe Van Vleck (March 4, 1833 – November 4, 1912) was an American mathematician and astronomer. He taught astronomy and mathematics at Wesleyan University in Middletown, Connecticut for more than 50 years (1853-1912), and served as acting university president twice.[1][2] The Van Vleck Observatory (at Wesleyan University)[3] and the crater Van Vleck on the Moon are named after him.