A sun, seen from far away
What Is a Star?
Every star in the sky is a sun. They look like specks because of the distance, and nothing else.
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Step 1 of 5
A star is a ball of gas, not a ball of fire.
Nothing is burning. Nothing could. There is nothing burning in the way a candle burns — that needs oxygen, and space has none. A star is hydrogen and helium, held together in a sphere by its own weight.
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Step 2 of 5
Its own weight is what makes it shine.
A star is so heavy that the middle is crushed to millions of degrees. At that temperature hydrogen atoms fuse together, and every fusion releases a little energy. That energy is the light.
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Step 3 of 5
It stays the same size because two things cancel.
Gravity pulls every part of the star inward. The energy from the core pushes outward. A star shining steadily is those two staying exactly level, sometimes for billions of years.
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Step 4 of 5
The specks are distance, not size.
The nearest star after the Sun is about 40 trillion kilometres away. Put our own Sun out there and it would look like exactly the same faint dot as all the others.
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Step 5 of 5
So they differ in almost every way except what they are.
Stars vary enormously in colour, size and lifetime — some last billions of years, some only millions. What they share is the same engine: weight, squeezing, and light coming out.
On a good dark night you can see a few thousand stars. Our galaxy holds a few hundred billion.
The short version
A star is a ball of gas heavy enough to crush its own middle into making light — every speck in the sky is a sun seen from very far away.
Try it yourself
Find the Sun in any list of stars by brightness. It is nowhere near the top; it just happens to be the one next door.