Stars always form within galaxies. Within galaxies, there are numerous fluffy clouds composed of gas and dust. These clouds are called nebulae.
Gravity creates dense clumps within these fluffy clouds – similar to raisins in a sponge cake. When one of these clumps starts to become more solid, firm, and rigid, its density also increases. Density represents the compactness, hardness, and high adhesive ability of an object.
The cores of these dense gas clumps also become hotter and, when they reach a certain temperature (millions of degrees), something very special begins to happen inside them. Hydrogen atoms combine to form helium. When hydrogen atoms combine to form helium, a nuclear fusion reaction occurs. This process releases a tremendous amount of energy, and it is the moment when a star is born.
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When hydrogen atoms combine to form helium, a nuclear fusion reaction occurs, releasing a tremendous amount of energy.
The Life and Death of a Star Like us, stars are born, live, and eventually die. The lifespan of a star depends on its mass at birth. Bright stars with small masses can live for an incredibly long time.
Our Sun is also a star. So far, the Sun has been around for about 4.5 billion years and is currently in the middle of its entire lifespan. In the next 5 billion years, the Sun will expand but then it will begin to fade away and eventually die. Its nuclear energy source will extinguish, and it will be left there, cold and lifeless, like a burnt-out piece of coal in a stove. Heavier stars than our Sun have a much shorter lifespan. The heaviest stars only live for about 1 million years, but their deaths are much more spectacular and exciting compared to the silent, gradual death of stars like our Sun. They go out in a massive explosion, and scientists call this phenomenon a supernova.
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A dusty nebula that will eventually transform into a star resides within the spiral arm of a galaxy, just like this.
We Are Made from Stardust
Have you ever heard someone say, “We are made of stardust”? Well, it’s true! Inside a star, helium atoms combine to create carbon, which is the origin of the chemicals that make up our bodies and all life on Earth.
There is still so much we don’t fully understand about the mysterious lives of stars. But luckily, we have large telescopes and satellites in space to capture increasingly clear and detailed images of the stars.