protostar - it's  tiny!

Hello, reader! Today the topic is . . . the Life Cycle of a Star! 
Yes, stars have life cycles, just like anything else.  Stars begin in a stellar nursery.  A stellar nursery is a nebula (a cloud of gas and dust) that houses young stars.  The next phase is a protostar, which is another word for a young star.  After a while, there's so much pressure that hydrogen and helium atoms start smashing into each other.  This creates nuclear fusion, which powers the star.  Nuclear fusion does two things:  it makes ignition and it makes lots of light and heat (otherwise known as energy).
This is a picture of a protostar.

Next, the star enters its mid-life.  This is known as its main sequence, and it is the longest part of a star's life. Our sun is in its main sequence right now.  Our sun is less than halfway through its life cycle.  It will live about 10 billion years. 
At mid-life, a star can be any size.  A star's size depends on how much matter it sucks in. 

red giant - it's huge!

Finally, a star reaches the end of its life.  How a star dies depends on its mass.  If the star is small, it will slowly lose layers and only its core, called a white dwarf, will remain. The lost layers of the star will form a cloud around it.  This is called a planetary nebula.  If the star is big, then it will become a red giant, expanding its outer layers.  See that picture off to the side?  That's a picture of a red giant. 







A star's life is a constant battle between nuclear power and gravity.  But in the end, gravity always wins.  It shoves the layers deep into the core.  But the core has too much pressure and releases a shockwave of nuclear energy called gamma rays.  These powerful energy bursts are also known as super-, or hyper-novas, depending on the star's size.