1848 – He discovered Hyperion and crepe ring of Saturn, independently of William Lassell.

1859 – He succeeded his father as director of Harvard College Observatory until his death.

1850 – He took the first photograph of a star (Vega).

1857 – The second photograph of a double star (Mizar).

         – He discovered numerous comets and calculated their orbits and studied Saturn and the Orion Nebula.

1865 – He died of tuberculosis on the 20th of May.