How Does the Sun Produce Light?

Visible Light

Look up in the sky at night, and you will see millions of little dots of light. Most of those are stars just like our sun, but they are too far away to produce light for us. We are close enough to this particular star for it to light and heat our entire planet.

The Process of Fusion

The sun lights up our planet through a process called fusion, whereby two atoms are fused together into a larger atom, releasing a great deal of energy. In the sun, two hydrogen atoms are fused together to form helium. Under normal circumstances, the two hydrogen atoms would repel each other. But, the intense gravitational force at work in our sun, and most other stars, is so great that it pulls the two atoms together. The enormous amount of heat from the core also helps fuse them together into helium, producing a great deal of energy.

Energy as Light

It is this energy in the form of thermal radiation that we see as visible light. Normally we wouldn't be able to see this, but because it is superheated (above 600 degrees Celsius), the waves become visible as light the human eye can see. If it were below this temperature, the waves would still be in the infrared spectrum, and invisible to the naked eye. Thus, we have what we call sunlight to light our days.