Short answers, pulled from the story.
The Sun formed about 4.6 billion years ago from the collapse of part of a giant molecular cloud that consisted mostly of hydrogen and helium. A shock wave from a nearby supernova likely triggered this formation by compressing matter within the cloud.
The Sun is now roughly halfway through its main-sequence stage and has not changed dramatically in over four billion years. It will remain fairly stable for about five billion more years before expanding into a subgiant and then into a red giant.
The core of the Sun extends from the centre to about 20% or 25% of the solar radius with a density of up to 150 grams per cubic centimeter. A temperature close to 15.7 million kelvin exists within this region while the surface temperature is about 5,800 kelvin.
Aristarchus of Samos proposed the theory that the Sun is the center around which planets orbit in the 3rd century BC. Nicolaus Copernicus later developed a detailed mathematical model of this heliocentric system in the 16th century.
It takes about 220 to 250 million Earth years to complete one revolution known as a galactic year. The Sun has done so approximately 20 times since its formation 4.6 billion years ago.