Description and illustration of Nicolaus Copernicus's heliocentric model of the solar system In a book called on the Revolutions of the Heavenly Bodies (that was published as Copernicus lay on
his deathbed), Copernicus proposed that the Sun, not the Earth, was the center of the Solar System
Such a model is called a heliocentric system. The ordering of the planets known to Copernicus in this
new system is illustrated in the following figure, which we recognize as the modern ordering of those
planets...