Light
The nature and properies of electromagnatic radiation

The Sun

The Sun is the center of our Solar system and is the main source of all light on Earth.

The Sun is a G-type main-sequence star that comprises about 99.86% of the mass of the Solar System. The Sun has an absolute magnitude of +4.83, estimated to be brighter than about 85% of the stars in the Milky Way, most of which are red dwarfs.

The Sun is by far the brightest object in the Earth's sky, with an apparent magnitude of −26.74. This is about 13 billion times brighter than the next brightest star, Sirius, which has an apparent magnitude of −1.46.

Thermonuclear reactions in its core produce high energy gamma-rays that are absorbed and converted into lower energy radiation by ionized atoms in its photosphere and chromosphere layers.

Earth atmosphere EM radiation absorption

Electromagnetic radiation

Synchronised oscillations (or their quanta, photons) of the electric and magnetic fields, propagating through space at the speed of ~300,000 km/s.

Visible light is a certain portion of electromagnetic spectrum between infrared (too weak to excite electrons in molecules) and ultraviolet (powerful enough to cause irreversible chemical reactions in organic matter).