The stars

Star is a ball of gas and dust that comes from stellar nebula. They are too small in space because they are too far from Earth. Our Sun is star that close to Earth and makes life on Earth planet. The advantage of stars is making energy by nuclear fusion.
Stars in space are about 20,000,000,000,000,000 and more. Stars visibility in space depends where they are located. Some of them close to our solar system and we can see from Earth in dark time of day or use the telescope. Some of them is too big, powerful even our Sun and they are located far from Earth we are not able to see. 

Supergiant stars

Red Giant

White Dwarf stars

Main sequence stars

Stars have four different types: Supergiant, Giant, Main sequence and White Dwarf. Supergiant stars are stars that have high level of magnitude and have massive size. Giant stars are stars that have luminosity bigger than main sequence stars and have medium size. Main sequence stars are all the remaining stars. White dwarf stars are stars that have low level of luminosity and have small size.
Stars have different colors and temperatures. Hot stars have blue color. Cooler stars have red color. The Sun is main sequence star has 5500K and color is yellow. Try to make easy life scientists created H-R Diagram. 

H-R Diagram

H-R Diagram is a graph that use to classify stars by their luminosity, spectral class, color and temperature.

Temperature is climate in stars. Temperature shows how stars are hotter or cooler. Brightness of stars shows how stars are bright or dim that called luminosity or magnitude. Main sequence, Giant and Supergiant stars have high level of brightness. Main sequence and white dwarf have low level of magnitude.

H-R Diagram is very useful diagram to classify stars. H-R diagram is best present colors of stars and spectral class. Each color has on spectral class. Blue has O, blue white – B, white – A, white yellow – F, yellow – G, orange – K, red – M. 

The stars heat made by nuclear fusion and happen in center of stars. Nuclear fusion is a process happens by nuclear reaction.Two molecules of hydrogen gas (H) change into molecules of helium (He). The result is making heat and energy.

Stars come from clouds of gas and dust called stellar nebula. By effect of gravity stars get smaller. As get smaller become hotter when in middle climate is enough hot will be nuclear reaction and star is born.

Stars life is similar human life but they live longer than people. They born develop from small size to big then they going to die. Stars come from stellar nebula. From stellar nebula become baby star called protostar. Stars divided by three categories: Sun like star, huge star, giant star.

Life cycle of sun like stars is developing by turning into Red Giant, Planetary Nebula, White Dwarf and Black Dwarf. Life cycle of Huge and Giant stars are almost similar. They turning  by Red Super Giant, Supernova. Some differences between these two types are after turning into Supernova Huge stars have Neutron star, Giant stars have Black Hole.