ix
geomagnetic perturbations and study their correlation with solar activity cycles; in
1863, he designed and built the thermoheliometer, a prototype of the bolometer.
Stellar Spectroscopy
Between 1863 and 1867, Secchi formulated one of the first spectral classifications
of stars, dividing them into three classes (α-Lyrae type, α-Herculis type, sunlike
type) and adding a fourth in 1869 (No. 152 Schjellerup type) and a fifth in 1872
(γ-Cassiopeiae type). He suggested the use of spectral analysis for measuring radial
velocities in star proper motions via measurement of the Doppler shift of the spectral lines. In 1872, he extended his classification by using an objective prism
(Lorenzo Respighi claimed priority in the use of this method). Secchi’s classification was the basis for all the later well-known classifications carried out at the
Harvard College Observatory (USA) at the end of the nineteenth century (Chinnici
2019: 167–177; Hearnshaw 1987: 57–66).
Solar System Astronomy
Thanks to the excellent optics of his Merz telescope, Secchi carried out detailed
observations of planets, satellites, and comets. He paid special attention to planets
Mars (McKim and Sheehan, Chap. 6, in this volume), Saturn, and Jupiter (trying to
photograph them), and was the first to observe the spectrum of Uranus, in 1869. In
1857, Secchi also obtained very detailed photographs of the Moon, which collected
in the first photographic atlas of the Moon (Chinnici 2019: 61–62). Regarding cometary astronomy, in 1852 he recovered the two parts of the periodic comet Biela,
which split in 1846, and, one year later, he discovered a comet, Secchi (1853-I)
(Chinnici 2019: 67–69). Secchi was also one of the first astronomers to examine
cometary spectra: in 1866, he observed the spectrum of the comet Tempel-Tuttle
(1866-I), confirming the results of the first observation of a cometary spectrum in
1864, and later carried out other interesting studies on comets (Chinnici 2019:
164–167).
Geodesy
In the years 1854–1855, he was charged by Pope Pius IX to measure a geodetic base
on Via Appia, to be used for linking the triangulation network of the Papal States, a
work initiated by Ruggiero Boscovich S. J. in the 1840s (Aebischer, Chap. 12, in
this volume).
Angelo Secchi: Biographic Notes (Chinnici 2019)
geomagnetic perturbations and study their correlation with solar activity cycles; in
1863, he designed and built the thermoheliometer, a prototype of the bolometer.
Stellar Spectroscopy
Between 1863 and 1867, Secchi formulated one of the first spectral classifications
of stars, dividing them into three classes (α-Lyrae type, α-Herculis type, sunlike
type) and adding a fourth in 1869 (No. 152 Schjellerup type) and a fifth in 1872
(γ-Cassiopeiae type). He suggested the use of spectral analysis for measuring radial
velocities in star proper motions via measurement of the Doppler shift of the spectral lines. In 1872, he extended his classification by using an objective prism
(Lorenzo Respighi claimed priority in the use of this method). Secchi’s classification was the basis for all the later well-known classifications carried out at the
Harvard College Observatory (USA) at the end of the nineteenth century (Chinnici
2019: 167–177; Hearnshaw 1987: 57–66).
Solar System Astronomy
Thanks to the excellent optics of his Merz telescope, Secchi carried out detailed
observations of planets, satellites, and comets. He paid special attention to planets
Mars (McKim and Sheehan, Chap. 6, in this volume), Saturn, and Jupiter (trying to
photograph them), and was the first to observe the spectrum of Uranus, in 1869. In
1857, Secchi also obtained very detailed photographs of the Moon, which collected
in the first photographic atlas of the Moon (Chinnici 2019: 61–62). Regarding cometary astronomy, in 1852 he recovered the two parts of the periodic comet Biela,
which split in 1846, and, one year later, he discovered a comet, Secchi (1853-I)
(Chinnici 2019: 67–69). Secchi was also one of the first astronomers to examine
cometary spectra: in 1866, he observed the spectrum of the comet Tempel-Tuttle
(1866-I), confirming the results of the first observation of a cometary spectrum in
1864, and later carried out other interesting studies on comets (Chinnici 2019:
164–167).
Geodesy
In the years 1854–1855, he was charged by Pope Pius IX to measure a geodetic base
on Via Appia, to be used for linking the triangulation network of the Papal States, a
work initiated by Ruggiero Boscovich S. J. in the 1840s (Aebischer, Chap. 12, in
this volume).
Angelo Secchi: Biographic Notes (Chinnici 2019)