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Section 4: The Spheres of the Planets Shatter
Since ancient times, the heavenly realm of the planets and stars was considered eternal and unchanging. Aristotle wrote that no changes had ever been recorded there. But observations of a new star and a comet altered that perception.
 
In 1572, Tycho Brahe discovered a new star (we would call it a supernova today) that appeared in the constellation Cassiopia, in the sphere of the fixed stars. The event proved that the realm of the stars underwent change after all, and the stars seemed suddenly less fixed in their orb.
In 1577, Brahe discovered a comet crashing through spaces where spheres of the planets were supposed to be. The discovery caused many astronomers to abandon the idea of planetary spheres and accept that the space they occupied was more fluid.

Aristotle wrote that the sphere is the one shape that our perfect cosmos must have. The new star in the heavens, signifying change and therefore imperfection, together with the loss of the planetary orbs, challenged the nested spheres model.

Tycho Brahe at his Uraniborg observatory. From Johannes Blaeu's Atlas Major, siue, Cosmographia Blauiana., 1662.
Blaeu
Beati
Brahe
Kepler
Above, clockwise from left:
* The planets are shown in a fluid medium, without solid spheres in Gabriele Beati, Sphaera Triplex Artificialis, Elementaris, ac Caelestis., 1662.
* Title page of the 1632 English translation of Tico Brahae, His Astronomicall Coniecture of the New and Much Admired [Star] Which Appered in theYear 1572. The new star was determined to be "above the moon."
* Johann Kepler's De Cometis Libelli Tres,1619, illustrates the trajectory of the comet of 1618, which passed through the planetary spheres.
Linda Hall Library of Science, Engineering & Technology
5109 Cherry Street, Kansas City, MO 64110
This exhibition is made possible by generous support from Mr. & Mrs. James B. Hebenstreit and Mrs. Lathrop M. Gates.