In the cloud of molecular hydrogen in the heart of the nebula original, over millennia, the nuclei of hydrogen compressed by gravity are transformed into helium, nuclear fusion starts, the gas ignites, the Sun was born in the darkness. The enormous power of the Sun is due to the contraction of the material of the original nebula. The Sun is really enormous, he has captured 99.86% of the total mass of dust and gas of the original nebula. Jupiter, the largest planet in the system, has captured the remaining 71%. The other planets have shared the residue of this gravitational evolution.
Our Sun is 1,392,000 km in diameter, is a yellow dwarf, a nuclear infernal cauldron, constantly buffeted by colossal explosions in space that send massive amounts of material. Since 4.57 billion years our sun in thermonuclear fusion in space sends a tremendous amount of energy, and it will last another 5 billion years. This thermonuclear power plant, is truly monstrous, it produces an enormous heat source and inexhaustible energy of 380 billion billion megawatts, equivalent to 3800 billion times the power of our 439 nuclear reactors in operation (2011).
Each square meter of the atmosphere receives 1,000 watts. In just one second, the Sun gives off unabated, more energy than produced the human civilization since birth and it lasts for 4 billion years. However, to 150 million km, the Earth receives only a tiny amount of this energy, just two billionths of radiation emitted. The actual mean temperature at Earth (15°C), is related to the average solar power received on Earth and Earth distance/Sun. The calculation of the received power on Earth in watts per square meter, is 239 wm2.