The Possibility of Life on Other Planets. Huygens’ “Cosmotheoros” in English

Huygens, Christiaan (1629-1695)

The Celestial Worlds Discover'd: Or, Conjectures Concerning the Inhabitants, Plants and Productions of the Worlds in the Planets. Written in Latin by Christianvs Hvygens, and inscrib'd to his brother Constantine Hvygens, Late Secretary to his Majesty King William. The Second Edition, corrected and enlarged.

London: Printed for James Knapton, at the Crown in St. Paul’s Church-yard, 1722


Octavo: 17.1 x 10.5 cm. vi, 162 pp. A-K8, L4. + five folding plates.

Modern blind ruled calf. A very fine copy, the contents crisp and bright copy. Illustrated with five, folding engravings: 1. The Copernican system; 2. Proportion of the Magnitude of the Planets, in respect of one another, and the Sun; 3. Jupiter and Saturn (and their satellites); 4. Saturn and its rings; 5. A schematic diagram showing the behavior of satellites in orbit around the planets.

This English edition of Huygens' posthumously published "Cosmotheoros" was first printed in the same year of the first Latin edition. In a letter dated January 9th, 1695, Huygens informed his brother, Constantijn, that he had finished the work. In that same year, Huygens died. In his will, he requested that his brother see that the work be published. In 1697, Constantijn too passed away before the printing was completed. The work finally appeared, printed by Adriaan Moetjens at The Hague, in 1698.

In this, his final work, Huygens explores the possibility of life on other planets, speculating that conditions elsewhere in the solar system might very well be like those on earth. "Among the essentials he reckoned the existence of water but perhaps with different properties from our own. For instance, it must have a lower freezing point on the colder planets. If some kind of human life exists, he suggested, there must be others forms of life upon which the human beings would be dependent." (Bell)

In the course of his thesis, Huygens discusses the planets; their distances from each other, the earth and the sun; their size and their motions (together with the motions of their orbiting satellites.) Huygens, the man who correctly identified Saturn as a ringed planet, shows how Saturn and its rings appear when viewed from Jupiter. Huygens also explains his modified Vortex theory, taking into account the gravitational ideas of Newton. The work also includes a refutation of the cosmology of the Jesuit polymath Athanasius Kircher.

"In the Copernican world system the earth holds no privileged position among the other planets. It would therefore be unreasonable to suppose that life should be restricted to the earth alone. There must be life on the other planets and living beings endowed with reason who can contemplate the richness of the creation, since in their absence this creation would be senseless and the earth, again, would have an unreasonably privileged position. In further discussions of the different functions of living organisms and rational beings, Huygens came to the conclusion that, in all probability, the plant and animal worlds of other planets are very like those of the earth. He also surmised that the inhabitants of other planets would have a culture similar to man's and would cultivate the sciences.

"In the second part of 'Cosmotheoros', Huygens discussed the different movements of the heavenly bodies and how they must appear to the inhabitants of the planets. He took the occasion to mention new advances in astronomy. In contrast to most other Huygensian writings, 'Cosmotheoros' has had wide appeal and a broad readership, and has been translated into several languages."(DSB).

"The work is written in an intimate vein, taking the form of a letter to Huygens' brother Constantijn. When Huygens outlines the Copernican theory he gives a diagram 'like what you have seen in my clock at home.' Perhaps he was referring to his machine for showing planetary motions. The reader recognizes much of Huygens' early work -the planetary magnitudes, the planets' distances from the earth and his views on the earth itself as a planet.

"At the end of the work Huygens states his modified vortex theory. 'I am of the opinion that every sun is surrounded with a whirlpool or Vortex of matter in a very swift motion; though not in the least like Descartes' either in bulk or manner of motion.' Descartes' views, Huygens asserted, needed to be corrected in the light of Newton's work, in particular to take account of the gravity of the planets towards the sun and how 'from that cause proceeds the ellipticity of the orbits of the planets discovered by Kepler.'" (Arthur Bell, "Christian Huygens and the development of science in the seventeenth century", pp. 200-202

ESTC T53996; Honeyman Catalogue, Part IV, 1732 (1698 ed.); cf. Lalande p. 334; Weidler p. 502; Grassi p. 357