The publication of the Tables of the Moon in 1857 represented a shift in precision for navigational and astronomical calculations, as these tables were adopted by the Nautical Almanac starting in 1862. Created by Peter Andreas Hansen, this work became a foundational element of lunar theory for decades before being refined by later researchers.
From Clockmaking to Celestial Mechanics
Born in 1795 in Tønder, Hansen initially pursued the trade of a watchmaker in Flensburg, Berlin, and Tønder. His scientific interests led him to Copenhagen in 1820 under the patronage of H.C. Schumacher. Between 1821 and 1825, he served as an assistant during the Danish survey, gaining essential experience at the Altona observatory. He moved to Gotha to direct the local observatory, a position he retained throughout his career despite offers to lead institutions in Dorpat, Helsinki, and Königsberg.
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Hansen devoted significant focus to gravitational astronomy. His 1838 publication, Fundamenta nova investigationis, proposed a revised lunar theory. His subsequent lunar tables were supported by the British government, which provided a £1000 grant. In 1854, he collaborated with Christian Olufsen to produce Solar Tables. During the same year, he identified that the accepted distance of the Sun was excessive by millions of miles, a correction derived from his study of lunar inequalities.
Geodetic Leadership and Honors
Hansen served as the first president of the Permanent Commission of the Central European Arc Measurement from 1864 to 1868. His contributions to science earned him the Copley Medal in 1850 and the Gold Medal of the Royal Astronomical Society in both 1842 and 1860. He was also honored with the Pour le Mérite for Sciences and Arts order and held memberships in organizations including the Royal Society, the Royal Swedish Academy of Sciences, and the American Academy of Arts and Sciences.
Fast facts
- Born: 1795, Tønder
- Died: 1874, Gotha
- Citizenship: Duchy of Schleswig
- Primary Occupation: Astronomer
- Education: University of Jena
- 1850 Award: Copley Medal
- 1860 Award: Gold Medal of the Royal Astronomical Society
- Memorial: Minor planet 4775 Hansen
Questions readers ask
What was Hansen's role in the development of lunar theory?
He developed the Tables of the Moon, which were used for decades in the Nautical Almanac to predict lunar positions until superseded by the work of E. W. Brown.
Which major scientific organizations recognized his work?
He was a member of the Royal Society, the Royal Swedish Academy of Sciences, the Accademia Nazionale dei Lincei, and the American Academy of Arts and Sciences, among others.
Achievements
- Copley Medal — 1850
- Pour le Mérite for Sciences and Arts order
- Foreign Member of the Royal Society — 1835
- Educated at University of Jena
- Fields of research: astrometry, astronomical observatory, astronomy and chronometry
