SPOERER, GUSTAV FRIEDRICH WILHELM

(b. Berlin, Germany, 23 October 1822; d. Giessen, Germany, 7 July 1895)

astronomy.

Spoerer attended the Friedrich Wilhelm Gymnasium in his native city and in 1840–1843 studied mathematics and astronomy at Berlin University, where he attended the lectures of Encke and Dove. He concluded his studies with the dissertation “De cometa qui a. 1723 apparuit,” defended on 14 December 1843. Thereafter Spoerer worked with Encke at the Berlin observatory, performing astronomical computations, and passed the examination for teaching mathematics and sciences in 1846. He taught subsequently at the secondary schools of Bromberg (now Bydgoszcz, Poland) and prenzlau, and in 1849 moved to Anklam, where he was awarded the title of professor.

In this era such a position afforded an opportunity for scientific work, which was expected by the Ministry of Education. Spoerer gave much more than was customary, especially in his astronomical observations, most of which concerned sunspots. For these efforts in 1868 the crown prince of Prussia presented Spoerer with a parallactic mounted refractor with a five-inch aperture, which made possible more and better observations. In the same year Spoerer participated in an expedition with Friedrich Tietjen and F. W. R. Engelmann to observe a total solar eclipse in India.

In 1874 Spoerer was appointed an observer at the planned astrophysical observatory in Potsdam and moved to that city. Until the building was completed, he continued to make observations of sunspots with his own instrument, mounted on a tower in the city.

Spoerer’s main accomplishments were his very careful observations of the sun. He determined the elements of the solar rotation and improved the law for the decrease of the rotation and improved the law for the decrease of the rotation of the sun from the equator to the poles, already derived by Carrington. His statistics for 1879–1893 contain much material on proper motions and on the evolution and distribution of sunspots during a sunspot period.

BIBLIOGRAPHY

Nearly each vol. of Astronomische Nachrichten from 55 (1861) to 125 (1890) contains contributions by Spoerer concerning observations of sunspots. Compilations are Beobachtungen der Sonnenflecken zu Anclam, 2 vols. (Leipzig, 1874–1876); and “Beobachtungen von Sonnenfiecken in den Jahren 1871 bis 1873,” Publikationen des Astrophysikalischen Observatoriums zu Potsdam, 1 , no. 1 (1878): “... in den Jahren 1874 bis 1879,” ibid., 2 , no. 1 (1880); “... in den Jahren 1880 bis 1884,” ibid., 4 , no, 4 (1886); and “... in den Jahren 1885 bis 1893,” ibid., 10 , no. 1 (1894).

There is an obituary by O. Lohse, in Vierteljahrsschrift der Astronomischen Gesellschaft, 30 (1895), 208–210.

H. Christ Freiesleben