The stars

1.What is a star?
star is a large balls of hot gas.they looks like small because they are a long way away,is very big.star
has many different colors and sizes of stars.stars are made in giant clouds of dust and gas called a
stellar nebula.the cloud get smaller because of gravity,after is very hot to became nuclear reactions make star born.

2.Types of stars
There are has 4 different types of stars:White dwarfs, Main sequence, Supergiants and Giants.the
stars can classified by their color,temperatures,sizes,name,ages and luminosity.a white dwarf is a
small,very dense,hot star that is made mostly of carbon.Super giant is the largest and most luminous
types of stars,being a dying star,Giant stars are cold and bright,Super giant stars and Main sequence
stars can be any color and size.

3.H-R Diagram
H-R Diagram is a graphical tool,use to classify stars luminosity,spectral type,color and temperature.

4.Nuclear Fusion
A star is like a largest nuclear fireplace.when two hydrogen gas molecules fuse together to create
a different atom.this process is know as nuclear fusion,it is this nuclear reaction that gives a star its
energy.H=Hydrogen  H=Helium

5.The life cycle of a star
Stars are born in nebula.huge clouds of dust and gas collapse under forming a body star call protostar,these young stars undergo further collapse,forming main sequence stars,stars expand as they grow old.the core contacts and the outer layers expand,cool,and become less bright.