In February of 1987, astronomers saw the closest supernova of modern times; it
was in the Large Magellanic Cloud, a neighboring dwarf galaxy.  This supernova,
named SN 1987A, is incontrovertible proof that the collapse of the core of
a massive star can produce a supernova.  Not only were neutrinos detected
from this explosion, as one expects in the birth of a neutron star from the collapse
of a stellar core, but also the star that exploded was observed many times before
the supernova and found to be massive.  The surprise is that the star
was a blue supergiant rather than the expected red supergiant.  Other striking features
of this supernova are its unusual chemical composition, its high expansion velocity,
its low luminosity, and the unusual shape of its nebula.  Some of these features are
tied to the star being a blue supergiant, while others are clues to why the star was
in a blue supergiant state when it exploded.