Stars shine because they are extremely hot (which is why fire gives off light — because it is hot). 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 which gives off energy that heats the star.

Why do stars shine only at night?

Stars are present in the sky at both day and night. ... During the day, the light of the Sun makes our sky so bright that we cannot see the much dimmer stars. At night, in the absence of the Sun, the sky becomes dark and the light of the stars can be seen. That is why, we are able to see the stars clearly only at night.

Where do stars get their light?

Stars are huge celestial bodies made mostly of hydrogen and helium that produce light and heat from the churning nuclear forges inside their cores. Aside from our sun, the dots of light we see in the sky are all light-years from Earth.