An American astronomer, Edwin Hubble (1889-1953)
specialized in unlocking some of the mysteries concerning galaxies. He
estimated the diameter of many, determining M31 Andromeda (pictured) and
M33, another spiral galaxy to be the nearest large galaxies. Andromeda
is a 'typical' spiral galaxy, of Sb class, meaning it has a small nucleus
with loosely wrapped 'arms'.
In 1885, a 'new star' was discovered in this region of the sky (within the galaxy). It was later determined to be a supernova, an exploding star of phenomenal proportions.
This supernova, named S Andromedae, had a peak luminosity of L=10 billion suns. It would take 10 billion of our suns to emit that much light. In fact, at its peak, S Andromedae emitted as much light in one second as our sun would emit in 300 years! Not even Ray Bans would help!