We can see other stars in the night sky when the Sun goes down. The energy from the Sun also causes weather and humidity on Earth. Plants turn the light into energy in a process called photosynthesis. The energy from the Sun supports almost all life on Earth by providing light for plants.
That will happen in about a billion years' time (10 9 years). When a star like the Sun gets old, it will expand in size and become a red giant star. The rest leaves as other kinds of electromagnetic radiation. The energy produced by stars moves ( radiates) away from them. Nuclear fusion changes hydrogen into helium. In the Sun (but not all stars) the change which takes place is the production of helium, with minute (very small) amounts of heavier elements. Nuclear fusion makes light and heat and makes bigger chemical elements.
Stars like the Sun are hot because this nuclear reaction happens inside them. The reaction changes hydrogen to helium and gives off heat. The amount of material in a star (its mass) is so huge that it starts a nuclear reaction going. The Sun is a star at the centre of the solar system. They give out heat and light because they are very hot. The Crab Nebula, remains of a supernova that was first seen around 1050 ADĪ star is a very large ball of bright glowing hot matter in space.
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