Stars shine 24/7, but during the day the atmosphere displays a “curtain ” of scattered sunlight in front of the celestial objects, which brightness is bigger than that of the stars, so they get “drowned” in daylight. Only a few objects are bright enough to be seen during the day: the Sun, of course, and the Moon.
Entire stars and our own Sun is just an example, are warm balls of lustrous plasma held together by their specific gravity. And the gravity of a star is very strong. Stars have continuously collided themselves inward, and the gravitational friction of this causes their interiors to heat up. A star like the Sun is an only 9980.33 Fahrenheit at its surface, but at its core, it can be 26999540.33 Fahrenheit
The extreme 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 numerous stages). This reaction releases a huge amount of energy in the form of gamma rays. These gamma rays are entrapped inside the star, and they push outward against the gravitational compression of the star. That’s why stars hold to a certain size and don’t continue producing. The gamma rays jump around in the star, trying to get out. They’re occupied by one atom and then emitted again. This can repeat 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 the photons have transferred the surface, they’ve wasted some of their energy, becoming visible light photons, and not the gamma rays they started to escape as. These photons jump off the surface of the Sun and head out in a straight line into space. They can travel endlessly if they don’t run into anything.
"The easy answer is that deep inside the core of the Sun, enough photons can collide into each other with enough speed that they stick together to form a helium nucleus and generate a large amount of energy at the same time. This process is called nuclear fusion. Every second, a star similar to our Sun changes 4 million tons of its material into heat and light through the method of nuclear fusion."
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| Nighttime Sky |
