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How did Nicolaus Copernicus explain the precession of the equinoxes?
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Nicolaus Copernicus
Portrait of Nicolaus Copernicus, 1580, from the Town Hall in ToruÅ, Poland; in the collection of Muzeum OkrÄgowe w Toruniu (Regional Museum in ToruÅ). In his book De revolutionibus, he proposed that the Sun was the center of the solar system and that the planets circle the Sun.
Nicolaus Copernicus explained the precession of the equinoxes by attributing the phenomenon to very slow, long-term changes in the direction of Earth's axis of rotation.1
In his heliocentric model, Copernicus proposed that Earth is a planet that not only orbits the Sun annually but also rotates daily on its own axis. He posited that the gradual shifting of this axis over time accounts for the observed precession. Constructing a model for this effect was a significant challenge for Copernicus, as he was attempting to account for very small, long-term astronomical changes using observations inherited from antiquity, the accuracy of which he could not always verify.12