1. Life Cycle of the Stars

2. The Making of the Star
Stars are formed in nebulae, which are large clouds of dust and gas.
Some of these clouds can get be up to 1 light year long, from base to tip.
The majority of the gas in these stellar nurseries is hydrogen.

3. Gravity Pulls It Together
Gravity at the center of the cloud pulls the dust together and starts to form a clump of matter.
As the ball of matter gets bigger, the force of gravity becomes stronger.
As the clump of matter grows, it begins to spin and heat up.

4. A Star is Born
When the core of the matter becomes hot enough, thermonuclear fusion begins.
This means that there is enough heat to turn hydrogen to helium.
Once this has happened a true star has been born.
The star shines with its own light.
A solar wind then blows away the rest of the dust and gas.

5. The Death of a Star
How a star ends its life depends on its mass or how much matter it was born with.
Low and medium mass stars will end up as white dwarfs.
Stars that started with a lot of mass may end their lives as black holes or neutron stars.

6. The Dying Star
When the star runs out of helium to burn, the star starts to collapse.
The star begins to collapse into itself. This collapse causes the star to compact.
After several more nuclear processes the star burns all the remaining helium and loses its outer layers. Now, the compacted core is exposed to the universe.

7. The White Dwarf
A White Dwarf is the end of the life cycle for Earth sized stars.
They produce a white-hot glow.

8. Neutron Stars
When a star that is the size of 10 to 20 solar masses runs out of fuel to burn, it explodes and the remaining matter collapses to become a neutron star.
This compact star is a few kilometers in diameter and resembles a giant nucleus made of neutrons.

9. Black Holes
When a star of more than 30 solar masses runs out of fuel, the collapse is so strong that no known force can stop it or resist it.
This collapse happens at a single point.
The matter of the star, its atoms and subatomic particles are squeezed out of existence, but the star remains its mass.
Not even light can escape, that is why it is called a black hole.