A space explosion is a gamma-ray burst. A gamma-ray burst is a short-lived burst of gamma-ray protons. We don't know what causes them and you can't see them with the naked eye. Some of these explosions are associated with a special type of supernovae, which are the explosions marking the deaths of especially massive stars. But gamma-ray bursts are the most powerful explosions the Universe has seen since the Big Bang. They occur approximately once per day and are brief, but intense, and last from a few milliseconds to a few hundred seconds.

Well, I think a general definition would be that a space explosion is a "rapid" and/or large release of energy -ultimately gravitational potential energy. There are several mechanisms that can cause explosions. One recent one that was in the press
( explosion.bubbles ), was an observation of an "explosion" due to a lot of matter falling into a super massive black hole at the center of a galaxy. As the matter falls into the black hole it releases energy which drives the explosion, somewhat similar to a big meteor falling onto/crashing into the Earth which I guess would be another type of space explosion.

Supernovae are also a type of explosion where the core of a star collapses under its own weight and explodes. Can you think of any other types of "space explosions?"