Over a hundred years ago, with the invention of photographic plates,
Supernova in OTHER GALAXIES began to be found. While we may only see a
supernova in our own galaxy every few hundred years, if we have hundreds
of galaxies to observe, we should see a supernova every year!
The number of ``external supernova'' began as just one or two a year in the early 1900s. In the 1950s the number jumped! People were making concentrated efforts to find these objects in old sky plates.
A list of all the Supernova known to date is found Here.
Two Kinds of Supernova
There are two basic classes, Type I and Type II.
Progenitor of Type II:
Progenitor of Type I:
Luckily, we don't need to have seen ahead of time, what the star was before it blew up! Types of Supernova are classified both on how the light evolves, and what the spectrum of the SN looked like:
Type I:
Type II:
A introduction to Supernova Taxonomy can be found Here