A star is a big ball of energy that glows which is made out of gas and dust.
The closest star to us is the sun. With out stars, humans would not be able live, the energy of stars fuels life.
There are billions and billions of starts, and they still counting.
Type Of Stars
Stars have many characteristics.( Color, Size, Luminosity, Temperature , Spectral Class, Age.)
Color defines what color of the star. It can be (White,Red,Blue,Yellow,Orange.)
Size shows how big a star is. Luminosity is how bright or dim is a star. Temperature is how hot or cold is a star. Spectral class indicates color and temperature of a star by a letter. Age is how young or old a star is.
The types of stars are White Dwarfs, Main sequence, Giants, and Super Giants. White dwarfs are small and old, they're also dim. Main sequence are young/middle age and there size,temperature,and color varies, our sun is a main sequence. Giant stars are middle age and big. There colors are orange and red, they are bright and cool. Super giants are huge. middle age/old, very bright and varieties of temperatures.
H-R Diagram
The Hertzsprung- Russell Diagram is a graph that astronomers use to classify stars based on their Color, Size, Luminosity, Temperature , Spectral Class, Age.
This graph is very useful in identifying stars, a good tool to find stars.
Nuclear Fusion
Nuclear fusion is the fuel of the stars. Nuclear reactions happen inside the star, the change of two gas molecules. Hydrogen gas into helium molecule. When the star runs out of this gases the stars have no more energy. Its like a fireplace, it will make fire intill it runs out of wood to burn.
Life of a Star
All stars live and die. They all start will stella nubula which is a cloud of gas and dust.
Sun like stars start with stella nebula like all others. It forms a star like the sun, then it becomes a red giant and it later explode making a planetary nebula. After it becomes a white dwarf which later forms into a black dwarf. Huge stars start like all the others. Huge stars as they age become Red Super Giants. The enormous star explode. This is called Supernova, which later forms a neutron star.
Lastly giant stars form from stella nebula. a giant stars get bigger as time go transforming into a Red Super Giant. Like huge stars it explodes.(Super Nova). Then it leaves a Black Hole in the universe.
