The Sun formed about 4.6 billion years ago from the gravitational collapse of a region within a large molecular cloud. Most of the matter gathered in the center, while the rest flattened into an orbiting disk that would become the Solar System. The central mass became increasingly hot and dense, eventually initiating thermonuclear fusion in its core. It is thought that almost all other stars form by this process.

This is an ancient solar symbol featuring a circle with its center marked with a dot (Unicode U+2609 ☉ preferably or U+2299 ⊙). It is the astronomical and astrological symbol for the Sun, and the ancient Egyptian sign for "sun" or "Ra" in the hieroglyphic writing system. The character for "sun" or "day" in early Chinese script was similar, but it has become square in modern script: 日 (ri).