How a Star Works

A star shines by nuclear fusion between particles at the center of the star. We saw this process earlier in the story. It is the force of gravity which presses the particles so close that they can fuse. During this process two protons are converted into neutrons and two positrons are emitted.

The positrons travel out from the center of the star and soon meet two electrons. These are identical in size but opposite in charge. Positrons are antimatter electrons. When matter meets antimatter they annihilate each other, converting their mass energy into radiation.

This radiation leaves the star as starlight. Also protons boil off the surface and travel out as a solar wind. This stage in a star's life, the "main sequence", lasts for billions of years. It is the stage that our Sun has reached.