A Titan of Astronomy and His Dying Wish: this week on the Storyteller's Night Sky

Oct 21, 2019

This image by Cellarius from 1660 shows the planetary system of Tycho Brahe, with Mercury and Venus orbiting the Sun, and Sun in orbit about the Earth, while Jupiter and Saturn orbit the whole.

This week marks the anniversary of the death of Tycho Brahe, on October 24 in 1601, the Danish astronomer whose dying wish to his assistant, Johannes Kepler, was something Kepler couldn’t fulfill.

Brahe, like Copernicus before him, did his work before the invention of the telescope, which meant he spent a tremendous amount of time calculating the motions of the heavens based on naked-eye observation, and striving to join his research with the philosophical and theological thought of the day. This thought was still dominated by the earth-centered system of Ptolemy, the omnipotence of God, and the unchangeable nature of the starry worlds beyond the Moon, as described by Aristotle.

In 1576, Brahe was gifted an island and an endowment from the King of Denmark to do his astronomical research, and here he built his Castle of the Heavens, where, for 20 years, he developed his theory about our planetary system. Brahe described Mercury and Venus orbiting the Sun, and the Sun, like the Moon, orbiting the Earth, with Jupiter and Saturn orbiting it all. This was a departure from the Copernican system that placed the Sun at the center of all planetary orbits. Brahe hoped Kepler would establish his system as the correct one, after his death.

And though Kepler tried, his own research led him to ultimately affirm the Sun-centered system of Copernicus, so that now, centuries later, we accept a concept about our planetery system that doesn’t quite match what we actually see: we see the Sun rise in the East, move overhead, and set in the West, though we accept that it is we who are moving. Besides, it would be too cumbersome at the end of the day to say “Let’s go watch the Earth turn east!” instead of rushing out to watch the sunset.