Comet Lexell (D/1770 L1) is a long-period comet discovered on 14 June 1770, by Charles Messier, but named for the Swedish astronomer Anders Johann Lexell (1740–1784) who first calculated its orbit. Several gravitational encounters with Jupiter have changed the comet's orbit so that it no longer comes close enough to Earth to be seen and it may even have been ejected from the Solar System altogether.