Our Sun is a massive sphere of superheated plasma. Its visible surface, the photosphere, is a turbulent layer dotted with sunspots and averaging a temperature of 5,500 K. Beneath this lies a 200,000 km thick convective zone, where heat rises and falls in massive loops. Deeper still is the 300,000 km thick radiative zone, where energy is transferred by radiation. At the very center is the core - the Sun's powerhouse. Here, temperatures soar to an incredible 15 million K.
This core generates energy through nuclear fusion, forcing hydrogen atoms to fuse into helium. In this process, a tiny amount of mass is converted into a vast amount of energy, as described by Einstein's E=mc². Every second, the Sun converts 700 million tonnes of hydrogen into helium, releasing power equivalent to 5 million tonnes of pure energy.
Here's the surprising part: while the Sun's total energy output is unimaginably large, its power density—the energy produced per cubic meter - is quite low. The core produces only about 276 watts per cubic meter, roughly the same heat output as a active compost heap!
So how does it produce so much total power? The answer is sheer scale. The core is 306,000 km in diameter, containing a staggering 15 million billion cubic meters. When you multiply that modest 276 watts by that immense volume, you get the colossal, life-giving furnace that powers our entire solar system.