SN is the beginning of the supernovas name, self explanatory because it stands for Super Nova.
The 4 digit number is the year it was discovered. The letter at the end is what order it was discovered in.
For example, SN 2012A is the first Supernova discovered in 2012. SN 2012L would be the 12th discovered in 2012. Lately it has become more common that double letters are needed, like SN 2012AA or AB with the ammount of supernovas we discover with new technology.
It's Called A Supernova
Nebula. Some nebulae are formed as the result of supernova explosions. The material thrown off from the supernova explosion is ionized by the supernova remnant. One of the best examples of this is the Crab Nebula, in Taurus. It is the result of a recorded supernova, SN 1054, in the year 1054 and at the centre of the nebula is a neutron star, created during the explosion.
SuperNova
Its called a Supernova.
A nova or a supernova
a super novaA supernova.
That's called a supernova.
The material sent into space by a supernova is called supernova ejecta. It includes elements such as hydrogen, helium, carbon, oxygen, and heavier elements created during the supernova explosion.
Nokia7210 supernova
An interstellar cloud.
An interstellar cloud.
There have been several recorded supernovae in the Milky Way. The earliest recorded Milky Way supernova was SN 185 (seen, as the name implies, in 185 C.E.), and the most recent supernova recorded was SN 1604 (seen in 1604 C.E.), or Kepler's Supernova.