THE BLACK HOLE MYSTERY

                    Have you heard amazing tales about black holes?
                    Black holes are the most powerful forces in the universe.  A black hole is so mighty that nothing can escape it, not even light.  It is so powerful that it bends time and space.  But no one will ever see one.  We have no way of discovering what goes on inside one.
                    The newspaper talked with the curator of astronomy at the Smithsonian Institution's National Air and Space Museum to discover more about this mysterious cosmic superpower.

A shining star goes dark
                     A super-big star might be millions of miles wide.  At the end of its life, it collapses into a point only a few miles wide.  This crunched star core becomes a black hole.
                     The Crab Nebula is the glowing gas from a supernova, formed after a star exploded.

A change in power
                      A star is a burning ball of gas.  When the star is "alive," gravity tries to pull the star matter into the center, or core.  At the same time, nuclear explosions in the star push out. 
                      The star stays balanced this way until it runs out of its nuclear fuel.  Then the star heats up until it explodes.
                       The outer gas is blown into space as a supernova.  The star's core collapses in seconds.  If the star is big enough, the smashed core becomes a black hole.  (Our sun is a star, but it is too small to ever become a black hole.)

Types of black holes
                      A black hole formed from a dying star is called a stellar black hole.  A star would need to be at least 25 times heavier than our sun to form a black hole when it dies and explodes.
                      There are also supermassive black holes that area million to a billion times bigger than our sun.  They may have grown and grown by "eating" stars and gas over billions of years.  Or maybe, two black holes collided, joining into one super black hole.