why do stars shinePosted by sulay on September 2nd, 2019 Head outside on a dark night and look up into the night sky. If you’re away from the bright city lights and it’s a clear night, you should see beautiful stars shining in the night. Just think, the light from those stars has traveled light-years through space to reach your eyes. But why do stars shine at all? Where is the light coming from? All stars, and our own Sun is just an example, are hot balls of glowing plasma held together by their own gravity. And the gravity of a star is very intense. Stars are continuously crushing themselves inward, and the gravitational friction of this causes their interiors to heat up. A star like the Sun is a mere 5,800 Kelvin at its surface, but at its core, it can be 15 million Kelvin – now that’s hot! The intense pressure and temperature at the core of a star allow nuclear fusion reactions to take place. This is where atoms of hydrogen are fused into atoms of helium (through several stages). This reaction releases an enormous amount of energy in the form of gamma rays. These gamma rays are trapped inside the star, and they push outward against the gravitational contraction of the star. That’s why stars hold to a certain size, and don’t continue contracting. The gamma rays jump around in the star, trying to get out. They’re absorbed by one atom, and then emitted again. This can happen many times a second, and a single photon can take 100,000 years to get from the core of the star to its surface. Like it? Share it! More by this author |