It was not until the sixteenth century that a mathematical model of a heliocentric system was presented by the Renaissance mathematician and astronomer  Nicolaus Copernicus, leading to the Copernican Revolution. In the following century, Johannes Kepler introduced elliptical orbits, and Galileo Galilei presented supporting observations made using a telescope.

With the observations of William Herschel, Friedrich Bessel, and other astronomers, it was realized that the Sun, while near the barycenter of the Solar System, was not at any center of the universe.

The Sun  is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radiation.