Born Pisa, (Italy), 16 December 1826

Died Florence, Italy, 20 September 1873

Giovan Donati was an observational astronomer and an early contributor to stellar spectroscopy. Pictures of the comet that he discovered are still widely reproduced in astronomy textbooks.

Donati was the son of Dr. P. Donati of Pisa. After preliminary studies at the University of Pisa under M. Mossotti, Giovan devoted himself to mathematics and original analytical researches. In 1852 he joined professor   Giovanni Amici at the Observatory of the Museum of Natural History, then known as La Specola. Two years later, Donati was made an aide-astronome, and following his discovery of the magnificent naked-eye comet C/1858 L1 that bears his name, astronome-adjoint. (He first saw the comet as a telescopic object on 2 June 1858.)

Donati succeeded Amici as director in 1864, the year he was elected an associate of the Royal Astronomical Society. During the period 1864–1872, Donati made strenuous efforts to set up a new national observatory at Arcetri adapted to the requirements of modern astronomy and terrestrial physics. His ambition was finally realized on 27 October 1872 when the Astrophysical Observatory at Arcetri, Florence (located near the house where   Galileo Galilei died), was inaugurated.

Donati was a pioneer in the field of stellar spectroscopy, a subject to which he wholly devoted himself following his visit to Spain to observe the total eclipse of the Sun in June 1860, and to which he made important contributions. The experience gained in this area induced him to examine the phenomena of scintillation. Between 1852 and 1864, he discovered five comets (including that which has his name), and during the early morning hours of 5/6 August 1864, he became the first to obtain a spectroscopic record of a comet when he observed and drew the spectrum of comet C/1864 N1 (Tempel). In 1869 he noted from observations of the great aurora of 4/5 February 1872 that certain phenomena were inconsistent with a purely atmospheric origin, something that led him to formulate what he called a cosmic meteorology. Between 1854 and 1873, Donati published roughly 100 papers, many of which were devoted to astrophysical subjects, atmospheric physics, and comets.

Donati was taken ill with Asiatic cholera while returning from Vienna, where he had represented the Italian government at the International Congress of Meteorology. Although seriously ill, he was enabled to return to his home and family at Florence, near the new observatory, but within a few hours succumbed to the disease.