Sun

The Sun was the star at the centre of the Solar System. It provided the gravitational centre around which the Earth orbited, and also provided that world with sufficient heat that allowed it to support liquid water, weather systems and life.

History
The Sun formed approximately 60 million years before the Earth, around 4.6 billion BU, from the gravitational collapse of a cloud of hydrogen. It is likely the collapse was triggered by a supernova. A protoplanetary disk orbited the young sun at this time, and this disk quickly evolved into an assortment of planets.

Physical properties
The Sun was a G2V spectral class yellow star (sometimes yellow dwarf).

It was 109 times the diameter of the Earth, 330,000 times the mass of the Earth and over a million times the volume of the Earth.

The Sun's surface had a temperature of 6000°C. The core had a temperature of 15 million°C, allowing for thermonuclear fusion to occur.