The Sun is the most amazing source of energy in our solar system. Every second that passes, the Sun's core produces energy through a nuclear fusion process equivalent to more than four million tons of TNT - an amount almost unimaginable for the human mind. To give perspective: all the nuclear weapons ever tested by humans on Earth, if exploded simultaneously, would still not come close to the energy the Sun produces in one second.
This process occurs through nuclear fusion in the Sun's core where the temperature reaches 15 million degrees Celsius and the pressure is 250 billion times the atmospheric pressure of Earth. In these extreme conditions, hydrogen atoms move very rapidly, allowing them to overcome the repulsive force between protons and combine to form helium nuclei. Every time four hydrogen atoms combine into one helium atom, a small portion of mass is lost and converted into energy according to Einstein's famous equation, E=mcยฒ.
Every second, the Sun converts approximately 600 million tons of hydrogen into helium. About 4 million tons of this mass is directly converted into energy. This energy then takes a very long time to travel from the core to the surface of the Sun - estimates suggest that the light photons produced in the core take between 10,000 to 170,000 years to reach the surface before subsequently traveling through space to Earth in just 8 minutes.
Although the amount of hydrogen used every second is extremely large by human standards, the Sun has enough hydrogen reserves to continue shining for about another 5 billion years before entering the final stage of its life.