Donati, Giovan Battista

(b. Pisa, Italy, 16 December 1826; d. Florence, Italy, 20 September 1873)

astronomy.

Donati studied at the University of Pisa, where he was a pupil of Mossotti. In 1852 he went to Florence, where he worked in the observatory, then called “La Specola.” It was directed at that time by Amici, whom Donati succeeded in April 1864. In the years 1854–1873 Donati published about 100 works, many of which were devoted to comets (on 2 June 1858 he discovered the comet that is named after him), astrophysics, and atmospheric physics.

His greatest achievement was the development of a new branch of astronomy based on Fraunhofer’s famous discovery and leading to the spectroscopic study of the stars. Indeed, after having been in Spain for the eclipse of the sun of June 1860, he devoted himself completely to the application of spectroscopy to the stars and published the results of his studies in Annali del Regio museo di fisica e storia naturale. He pointed out the differences between the spectra of fifteen principal stars and that of the sun. He was also the first to obtain the spectrum of a comet and to interpret the observed features. The sun also was an object of his studies, both as an isolated body and in relation to other celestial bodies.

In 1868 he published two papers on the sun, one (in Nuova antologia, 8 , 334–353) on determining its distance from the earth and the other (ibid., 9 , 60–93) on its physical structure. In 1869 he noted that certain phenomena heretofore thought to have had an atmospheric source actually originated in higher regions. He thus formulated the basis of a cosmic meteorology.

His experimental work brought forth first of all a spectroscope with five prisms, which was used in Sicily to observe an eclipse in 1870. He also devised a spectroscope of twenty-five prisms; it was exhibited in Vienna and Donati used it to make a series of remarkable observations in 1872. He noted the results that he obtained through the use of these spectroscopes and described them in Rapporti sulle osservazioni dell’eclisse totale di sole del 22 dicembre 1870 and in Memorie delta Società degli spettroscopisti italiani.

During the years 1864–1872 Donati was further occupied with the construction of a new observatory at Arcetri, near the house where Galileo died. The observatory was dedicated on 27 October 1872.

Donati’s important work “Sul modo con cui si propagarono i fenomeni luminosi della grande aurora boreale osservata nella notte dal 4 al 5 febbraio 1872” was the first number of the intended periodical Memorie del Regio osservatorio di Firenze ad Arcetri. (Publication of the Memorie ceased with Donati’s death; twenty years later A. Abetti started a new series with the title Osservazioni e memorie dell’osservatorio astrofisico di Arcetri.)

Donati died of cholera returning from Vienna, where he had taken part in the International Congress of Meteorology.

BIBLIOGRAPHY

Donati’s works include “Intorno alle strie degli spettri stellari,” in Annali del Regio museo di fisica e storia naturale di Firenze per il 1865, n.s. 1 (1866). 1–21; “Intorno alle osservazioni fatte a Torreblanca in Spagna dell’eclisse totale di sole del 18 luglio 1860,” ibid., 21–37; “Osservazioni di comete fatte all’Osservatorio del Regio museo di Firenze dall’anno 1854 fino al 1860,” ibid., 37–63; “Osservazioni spettroscopiche di macchie solari fatte a Firenze,” in Memorie della Società dei spettroscopisti italiani raccolte e pubblicate per cura del Prof. P. Tacchini, I (Palermo, 1871), 52–55; Rapporti sulle osservazioni dell’eclisse totale di sole del 22 Dicembre 1870 eseguite in Sicilia dalla Commissione Italiana (Palermo, 1872), pp. 31–39; and “Sul modo con cui si propagarono i fenomeni luminosi della grande aurora boreale osservata nella notte dal 4 al 5 febbraio 1872,” in Memorie del Regio osservatorio di Firenze ad Arcetri (Florence, 1873), pp. 5–31.

Maria Luisa Righini Bonelli