Space Information for Kids - What is a Supernova?

Space Information for Kids - What is a Supernova?

Throughout the universe, there are great clouds of gas and dust.

These clouds are called nebulae. 

In larger nebulae, stars may form. The process begins when gravity pulls the gas and dust particles together.
As the mass of particles becomes tightly packed, or compressed, it heats up. In time, the temperature inside rises to about 2,000,000 °F (1,100,000 °C).
At such temperatures, atoms of hydrogen gas begin to combine, or fuse, together to form helium gas.
As they do so, they release an enormous amount of energy as light and heat.
The mass of gas and dust begins to shine—as a star.

...and dies.

A star the size of the sun has a long life. 

The sun is now about 4.6 billion years old and will probably stay as it is for another 5 billion years.
Then, scientists believe, it will run out of hydrogen "fuel" and begin to die.
First, it will swell in size and become a type of star we call a red giant.
Then it will slowly shrink again, becoming smaller and smaller, until it is not much bigger than the earth.
It will become a body called a white dwarf.
For their size, white dwarfs are very heavy.
A teaspoonful of material from a white dwarf weighs many tons!

What is a Supernova?

Big, heavy stars die spectacular deaths. They swell up into enormous super giants, many times their own size.
Then, they blast themselves apart in a mighty explosion called a supernova.
After a supernova, a tiny star sometimes remains.
It is called a neutron star, because it is made up of tiny particles called neutrons.
Very heavy stars do not form neutron stars.
They continue collapsing under gravity until they crush themselves into a very small space.
All that remains is a small area with an enormous gravity. This swallows up anything nearby, even light.

For this reason we call it a black hole.