How is a star born?

Have you ever looked up on a clear, dark night and seen stars twinkling far away? Each of those tiny lights is a sun, glowing far across space. Every one of them had a beginning, a time before it ever shone. So how is a star born?

A star begins inside a nebula, which means a giant cloud of gas and dust floating in space. A nebula is cold and dark, and it stretches far wider than our Sun. Its gas and dust are everything a new star will be made from.

Inside the nebula, gravity tugs every bit of gas and dust toward the others. Little by little, the bits drift closer together. Because of that pull, some parts of the nebula grow thicker than the rest.

In one thick part, the gas and dust gather into a clump. A bigger clump pulls harder, so it draws in even more gas from the nebula around it. That is how the clump keeps growing.

Gravity squeezes the growing clump tighter and tighter, until it becomes a round ball of gas. Deep in its middle, the tiny bits of gas are pressed closer than anywhere else. What do you think happens to the middle of the ball as gravity squeezes it?

The middle gets hotter! As the ball shrinks, its tiny bits crowd in and bump into each other faster, and all that bumping makes heat. The ball grows warm, but it is not a star yet.

For a long, long time, gravity keeps squeezing and the middle keeps heating up. Bit by bit, it becomes far hotter than any fire on Earth. Only that much heat can start the next step.

Deep in the hot middle, the tiny bits of gas now crash together hard enough to stick and join into new bits. Each time two bits join, they give off a burst of light and heat. Huge numbers of these joinings happen every single moment.

All that light and heat pours out from the middle of the ball. It shines out through the gas and dust around it, and the whole ball glows bright. A new star is born!

Our key word was nebula. A star is born when gravity squeezes the gas and dust of a nebula into a tight ball, until its middle grows hot enough for tiny bits to join and pour out light.

Next time you see a star twinkle, you can picture the big, dark cloud where it first began to glow. Sweet dreams under all those shining stars.