A supernova discovered on the 24th February, 1987 by Ian Shelton (University of Toronto*) at Las Campanas Observatory**, Chile.
SN 1987A was created when the core of the star Sanduleak -69o 202 collapsed, creating a type II supernova. Sanduleak -69o 202 was blue supergiant about 20 times the size of Sol, located 169,000 light years away in the Tarantula Nebula, a section of the Large Magellanic Cloud galaxy.
It was not believed until after SN 1987A that blue supergiants could produce type II supernovae. Previously only red supergiants were thought to do so. From the example set by SN 1987A, it is found that blue supergiants can create supernovae, but that they will be quicker and fainter than those with progenitors that are red supergiants.
SN 1987A is the only supernova to have been visible to the naked eye since SN 1604, or Kepler’s Supernova discovered in 1604. This is not due to its size, but the fact that is so close (astronomically speaking) to us.
An image of the remnant of 1987A can be found at http://zebu.uoregon.edu/~soper/ImStarDeath/SN1987A_des.jpg