Why do stars shine?

Stars are known to be the glowing bodies in our night sky that fill our view whenever we lookup.

They have inspired writings, music, art, culture, and of course, science. A star is an astronomical object consisting of a luminous spheroid of plasma held together by its gravity.

To simplify, a star is a large celestial body in space.

It is a luminous object that emits its light and is spheroid in shape. It is made of plasma, which is the fourth state of matter.

Plasma, in physics, is an electrically conducting medium in which there are roughly equal numbers of positively and negatively charged particles, produced when the atoms in a gas become ionized.
 
A star is held together by the strong pull of its gravity due to its generally large mass.

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. 
 
The intense pressure and temperature at the core of a star allow nuclear fusion reactions to take place.

This is the point at which atoms of hydrogen are fused into atoms of helium.

This occurs through several stages.

This reaction ends up releasing enormous amounts 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.

These rays jump around in the star, constantly trying to escape.

They end up being absorbed by one atom, eventually being 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.
 
When these photons end up teaching the surface, they have already lost some of their energy.

They turn into visible light photons instead of the gamma rays they initially started as.

These photons leap off the surface of the Sun and head out in a straight line into space.

They can travel forever if they don’t run into anything.
 
When we see stars such as Sirius, which is located about 8 light-years away from us, we are witnessing the photons that left the surface of the star 8 years ago and traveled through space, without running into anything.

Our eyeballs are the first thing those photons have encountered.
 
Coming to the main question, why do stars shine?

To simply answer the question, the reason stars shine is because they have huge fusion reactors in their cores releasing a tremendous amount of energy.
 
Stars shine because they are extremely hot, the same reason why fire also gives off light.

The source of their energy is nuclear reactions going on deep inside the stars.

In most stars, like our sun, hydrogen is being converted into helium, a process that gives off energy that heats the star.

This warms the outer layers of the star, which gives off heat and light.
 
These luminous objects have fascinated us through multiple generations and still do.

Their glow is a defining feature of stars, and this inspires so much of the world.

We hope to learn more about these bodies as technology advances.