* Astronomy

Giovanni Battista Donati ; 16 December 1826, Pisa, Italy - 20 September 1873, Florence, Italy) was an Italian astronomer.
Donati pioneered spectroscopy of comets to determine their physical composition, in particular with the comet 1864b, which spectrum he found containing three emitting lines which would four years later be identified by William Huggins to be carbon. He discovered that the spectrum changed when a comet approached the Sun, and that heating caused it to emit its own light rather than reflected sunlight: he concluded that the composition of comets is, at least in part, gaseous. Donati was also a pioneer in the spectroscopic study of the stars and the sun.
Between 1854 and 1864 he discovered six new comets, including the spectacular Comet Donati (C/1858 L1), found in 1858.
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