How did Copernicus test his hypotheis in the heliocentric theory?
Copernicus was a theoretician, and not an observer. He based his theory on philosophic grounds, not empirical. However, at around the same time, Tycho Brahe in Denmark began to make accurate measurements of planetary positions, using huge non-optical instruments, as the telescope hadn’t been invented yet. His observations were remarkably accurate and enabled Johannes Kepler to discover that the orbits of the panets weren’t circular, but were elliptical. When Galileo started to use the telescope for astronomy in 1609, he discovered evidence in the motions of Jupiter’s moons which confirmed Copernicus’ theory once and for all.
He gathered no data and made no experimental observations to prove or disprove it. Copernicus’s theory was based purely on reading Aristarchus’s ideas (a Greek who proposed a Sun centered solar system around the same time Aristotle proposed an Earth centered solar system) and philosophical reasoning. Aristotle’s idea that everything orbited the Earth didn’t match actual observations, so his theory had to be constantly modified by adding celestial spheres and epicycles (circular orbits that themselves orbited in a circle around something else). The model became incredibly complex, but was forced to approximately match real observations. Copernicus felt God wouldn’t create such a complex universe and that there must be something wrong with the Aristotle model. So, he resurrected the Aristarchus model that put the Sun in the center of the solar system and proposed that the planets orbited the Sun in circular orbits. That idea definitely didn’t match observations (even though the Sun is th
Coppernicus didn’t test his theory – had he done so he’d have found it was wrong. He correctly put the sun at the centre of the solar system, but he still thought the planetary orbits were circular and had to hang on to the idea of epicycles. Even Kepler didn’t prove the heliocentric theory – he came up with a set of laws which accurately described the observed movement of the planets, but there was no theoretical basis for them. That didn’t happen until Newton came up with his theory of gravity.
