Today, I'd say that we're at least fairly certain that the Earth (and all the other planets) revolve around the sun, and not the other way around. I don't want to rule out some crazies out there, I mean, the world does have 7 billion people in it. But let's just go with it. We know that the heliocentric model for our solar system is the correct one, and we have Nicolaus Copernicus to thank for that.
Not just Copernicus, of course. Heliocentrism wasn't his idea - it was proposed as early as the 3rd century BC. But Copernicus is credited with forming the comprehensive mathematical heliocentric model and his book De revolutionibus orbium coelestium (On the Revolutions of the Celestial Spheres) is considered one of the most important works in the history of science.
After the publication of Celestial Spheres, the so-called Copernican Revolution began, ushering the world into the Scientific Revolution.
Copernicus, a true Renaissance Man, served as a mathematician, astronomer, Catholic cleric, artist, physician, economist, and is said to have spoken at least four languages.
Copernicus was born on February 19th, 1473 and died in 1543 at the age of 70. Today's animated Google Doodle celebrates his 540th birthday.