In the 1500s, people believed that the Earth was the center of the universe, and everything revolved around our planet. A revolutionary idea was published in 1543 by Nicolaus Copernicus. He provided mathematical evidence for a heliocentric universe, one where the planets in the solar system revolve around the sun. This theory was formed two hundred years before the telescope was invented, using his eyes to watch the heavens. Unfortunately, Copernicus never knew what a change his theory would cause in the scientific community, as his theory was published at the end of his life, and was not widely accepted until about 100 years after his death.