Scientists observe a superluminous supernova that appears to have exploded twice

Supernovae are among the most violent phenomena in the universe. They are huge explosions that end the lives of certain types of stars. These explosions release immense amounts of energy, so much that some can be observed from Earth with the naked eye, appearing as points of light that are briefly brighter than all the millions of stars in the galaxies where they are found. Following an intense burst of light lasting a few weeks, supernovae start to fade gradually until they have effectively bur...