In 1920, British astrophysicist Arthur Eddington was the first to discover why the stars shine. Sunlight is due to nuclear fusions that occur inside.
The Sun is composed of gases, mainly hydrogen, which is the simplest atom. A hydrogen atom contains a proton and an electron. As gravity groups the hydrogen atoms in the Sun's core, they are increasingly imprisoned with each other. The pressure and temperature increase, until the atoms begin to fuse. Up to four hydrogen atoms merge into one, with two protons and two electrons. This new atom is helium.
In the fusion process, part of the mass of the atom is lost. That is, the mass of the helium atom is not the sum of the mass of the hydrogen atoms, but is smaller. This difference in mass is what is transformed into energy, which is dismissed in the form of light.
Every second, the Sun transforms millions of tons of hydrogen atoms into helium atoms. This is what nuclear reactions inside a star consist of. There are so many mergers that the amount of energy is immense. The energy generated by the Sun in a second would be enough to supply the Earth for a million years. But only a small part of that energy comes to Earth. The majority is expanded by the rest of the Solar System.
The Sun's energy is released into space in the form of radiation, in all its variables: radio waves, microwaves, infrared radiation (heat), visible light, ultraviolet radiation, X-rays and gamma rays. Radio waves and microwaves are the weakest radiation, while gamma radiation is the most powerful that exists.
Since the energy in the core of the Sun is produced until it reaches the surface and is released into space, hundreds of thousands of years pass. Along the way, some of that energy loses power and is therefore emitted in different forms of radiation. Even so, much of the energy that the Sun gives off is still gamma rays. Visible light is solar energy that has lost part of its power. Since leaving the Sun, it takes 8 minutes to reach Earth.
The sun does not always shine with the same intensity. It varies depending on the solar cycles. The Sun shines brighter when the number of sunspots increases, which is when the Sun is most active.
|◄ Previous||Next ►|
|Advanced Solar System||Solar cycles|