Because of the distances involved, a supernova could have occured today, but we wouldn't know about it for thousands or billions of years. As with all things in space, what we observe is what was, not what is.
See related questions for last observed supernova.
It is iron.
It is yes
No, not a supernova.
it is Supernova
supernova
it is a steller explosion
Supernova
SuperNova
A supernova.
The energy output of a supernova explosion is equivalent to the energy produced by the sun over its entire lifetime.
No. A supernova is a massive explosion, usually from a dying supermassive star.
supernova