A supernova is the explosion of a star after it has gone through
all the phases of nuclear fusion. As the star burns down some of
its matter flows into its core to a point where the core
is so heavy it cannot withstand its own gravitational force. At
this point the core collapses and a huge explosion occurs. This
is a super nova. A star must be of a certain mass to get to this
point though. The sun, for example does not have enough
mass to become a supernova. There is also another type of
supernova that only occurs when there are two stars that orbit
the same point. When one of the start is a white dwarf, which is
a star near the end of its life that has collapsed into a size
similar to that of Earth's, and it steal matter from the other
star, it eventually accumulates too much matter and explodes in
a supernova.
www.dailygalaxy.com
The supernovas that we can see usually
occur in other galaxies because the ones that occur
in our galaxy accumulate too much dust for us to see
through. Even though supernovas only burn for a
short period of time they have taught us a lot about
the universe that we live in. For example we have
learned from the way the debris of a supernova moves
that our universe is expanding. We also know that a
lot of the new material in the universe comes from
exploding stars that most things around us was
likely part of a star at one point or another.
guardianly.com
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Fun Fact:
In 2011 a 10 year old girl from Canada
discovered a supernova by just looking at pictures
she had taken of the sky.
