Stars are immense, luminous spheres of plasma held together by their own gravity, primarily composed of hydrogen and helium. At their cores, they undergo a process called nuclear fusion, which converts hydrogen into helium and releases a staggering amount of energy as light and heat. This energy not only makes them shine across vast distances but also provides the outward pressure necessary to prevent the star from collapsing under its own massive weight. Our own Sun is the closest example of such a star, acting as the primary energy source for life on Earth.
The life cycle of a star begins in nebulae, which are giant clouds of gas and dust that act as “stellar nurseries”. When regions within these clouds collapse under gravity, they form protostars that eventually ignite once the core temperature is high enough for fusion. A star’s lifespan and eventual fate depend largely on its initial mass: smaller stars, like red dwarfs, can burn for trillions of years, while massive stars burn through their fuel quickly and may end their lives in spectacular explosions known as supernovae. These explosions are vital for the universe, as they scatter heavy elements like carbon and oxygen that are essential for forming planets and life.