New York Society Library


NYSL: Johannes Kepler


Pragae: Paul Sessi, 1606. 1st ed.

In September 1604, a brilliant new star appeared in the sky within a few degrees of Jupiter, Saturn and Mars. Its presence caused a sensation. In Prague, the new star caught the attention of the German mathematician Johannes Kepler, who was attached to the court of the emperor Rudolf II. He observed it for seventeen months until it faded from view. The telescope had not yet been invented.

In De stella nova Kepler describes the nova's appearance and possible origin and draws an analogy between the nova of 1604 and the star of the Magi. He settles upon 5 B.C. as the year of Christ's birth, a date commonly accepted today. He also argues that stars are not suns. Kepler speculates that the appearance of the new star will lead to the conversion of the Indians in America, the migration to the New World, the downfall of Islam. Such astrological predictions, even for astronomers of Kepler's rank, were commonplace.

NYSL: De Stella Nova in Pede Serpentarii Kepler's passion for the heavens dates from his childhood. When he was six years old he watched the great comet of 1577 with his mother. Three years later he saw the moon in eclipse. Kepler, who suffered from weakened eyesight all his life—the effects of early smallpox—never let it stand in his way. His first observatory was a wooden staff suspended from a rope. "Hold your laughter, friends. . ." he said.

Kepler's faith in his powers of observation was well-deserved. The impact of De stella nova was immense. It served as a liberating influence for many astronomers, especially Galileo. Under the weight of new evidence, the old Ptolemaic system was beginning to crumble. Kepler went on to discover his three laws of planetary motion, which would revolutionize astronomy. Of the solar system, he once wrote, "I contemplate its beauty with incredible and ravishing delight."

Special Collections
NYSL Main Page