A new discovery by astronomers reveals that a pre-supernova stars may show signs of change for a few months before the big explosion. It flows out a material into space and creates a dense gas shell around themselves.

According to NASA, a supernova is a large explosion that occurs during an end of a star's life cycle. It is the largest explosion that happens in space.

Johannes Kepler who discovered the last observed supernova in the Milky Way in 1604, saw explosions from these stars and said that often these events may be seen in other galaxies. However, due to a dust that blocks the visibility from the Earth, it is really difficult to see the Milky Way. These usually happen when there is a change in the core or center of a star.

A research led by Weizmann Institute of Science researchers shows that the stars that become core-collapse supernova might already show a great change for a several months before the big explosion. Most of the common types of supernova include red supergiants which scientists thought the ancestor of supernovas. The iron core of these massive stars that collapse on itself and outer layers are thrown out into space in a great big explosion.

Per Science Daily, astrophysicists from different parts globe scan the California night sky for the sudden appearance of new astronomical transients. They want to search for some new sites to let them tell whether it is a new supernova or not. "We had x-rays, ultraviolet, four spectroscopic measurements from between six and ten-hour post-explosion to work with," as per Dr. Ofer Yaron, Weizmann Institute's Particle Physics and Astrophysics Department.

They still do not really understand the process of a "supernova". But these findings are raising new questions and ideas with the globe-spanning collaboration that enables to alert different types of telescopes to train for the event. They are getting closer and closer to understanding what happens and how stars end their life and what leads up to the final explosion.