# 5.2: The Center of the Universe


## The Center of the Universe

Simply stated, the Universe is huge. It is hard for most of us to comprehend the scale and size of our own Earth-Moon system, the distance to the Sun, our Solar System, or the Milky Way Galaxy. It is understandable that ancient peoples had challenges comprehending the arrangement and make-up of even the Solar System, nonetheless the Milky Way Galaxy and the Universe.

Most early Solar System models placed Earth as the center of the Solar System — and most-often the Universe. The reasoning made sense: everything appeared to go around Earth. Aristotle in the 4 th Century BC was one of the earliest proponents of an Earth-centered Solar System — a geocentric model. Yet, one of the earliest Solar System models, that of Aristarchus in the 3 rd Century BC, did correctly place the Sun in the center of the Solar System. Most accepted the Earth-centered Solar System which was refined by the Greek philosopher Claudius Ptolemy in the 2 nd Century AD. This geocentric Solar System model was accepted by both scientific and religious circles until the work of Nicolas Copernicus (1543) and observations with the telescope of Galileo Galilei (1609) showed the Sun was the center of the Solar System, a heliocentric model. (1)