A large new comet, visible to the naked eye, is observed all over the northern hemisphere

A comet, later designated "Comet C/1860 M1" but known popularly as the "Great Comet of 1860," was discovered simultaneously by astronomers all over Europe and the eastern United States.  Seen first on June 18, 1860 in Italy, reports of sightings poured in over the following days, all noting its brilliance and visibility to the naked eye.  It came closest to Earth on July 11, 1860 and was last seen on October, 18, 1860.  (By John Osborne)