• DOI:10.1177/002182869202300307
• Corpus ID: 117859392

Hegel and the Seven Planets

@article{Craig1992HegelAT,
  title={Hegel and the Seven Planets},
  author={Edward Craig and Michael A. Hoskin},
  journal={Journal for the History of Astronomy},
  year={1992},
  volume={23},
  pages={208 - 210}
}

• E. Craig, M. Hoskin
• Published 1 August 1992
• Physics, Geology
• Journal for the History of Astronomy

In the Copernican system, Earth-based observers were able to derive the radii of the planetary orbits in terms of the (mean) Earth-Sun distance, from observation and elementary trigonometry. Before the end of the sixteenth century, Kepler had been struck by the disproportionate gap between the orbits of the fourth planet, Mars, and the fifth, Jupiter, and had considered the possibility of filling the gap with a planet hitherto unobserved.' Although Kepler eventually found an alternative way of dealing with this apparent anomaly in the planetary system, other astronomers continued to feel uncomfortable with the system as presently understood, and the formulation in the last quarter of the eighteenth century of the arithmetical relation known as 'Bode's Law' served to bring matters to a head.' In this Law, the distances from the Sun of the six known planets were seen as roughly proportional to the numbers 4, 4 + 3, 4 + 2.3, 4 + 4.3, 4 + 16.3 and 4 + 32.3, but no known planet corresponded to the term 4+8.3. The Law received unexpected support from the discovery by William Herschel in 1781 of the planet Uranus, whose solar distance corresponded well with the next term in the arithmetical sequence, 4 +64.3; and at the close of the century Franz Xaver von Zach and others joined forces to organize a systematic searchfor the supposed missing planet between Mars and Jupiter corresponding to the term 4 +8.3. On I January 1801, before the invitation to join in the search had had time to reach him, Giuseppe Piazzi of Palermo discovered a planet (or, more exactly, what was to prove a very small but otherwise planet-like body) that was found to have an orbit of the appropriate size.' But news of the existence of this eighth planet (now known as the asteroid or minor planet Ceres) had barely had time to reach Germany when the young philosopher Georg Wilhelm Friedrich Hegel (1770-1831) published his docent thesis, Dissertatio philosophica de orbitis planetarum. 5 Hegel is commonly ridiculed by historians of astronomy as having 'demonstrated' the impossibility of there being an eighth planet at the very moment that an eighth planet was being discovered. So for example we read that in the dissertation Hegel "proved by the clearest logic that the number of planets could not exceed seven"," or again, that Hegel" 'logically proved' that the number of planets could not exceed seven".' Indeed, so frequently is Hegel castigated for this that a recent writer felt compelled to follow custom: