While it's tempting to say Nicolaus Copernicus discovered that planets orbit the sun, it's a bit more nuanced than that.

Here's why:

* Ancient Greek astronomers: The idea of a heliocentric (sun-centered) universe was proposed by Greek philosophers like Aristarchus of Samos around the 3rd century BC.

* Copernicus's contribution: Copernicus revived the heliocentric model in his book "De Revolutionibus Orbium Coelestium" (On the Revolutions of the Heavenly Spheres) published in 1543. He provided mathematical and observational evidence to support the idea, which challenged the prevailing geocentric (Earth-centered) model.

* Galileo Galilei: Galileo's observations with his telescope in the early 17th century provided further evidence for the heliocentric model, such as the phases of Venus, which could only be explained by Venus orbiting the Sun.

So, while Aristarchus first proposed the heliocentric model, Copernicus is credited with reviving and providing evidence for it, making it a credible scientific theory. Galileo's observations played a crucial role in solidifying this theory.