Astronomers have spotted what they say is the brightest supernova to have ever been recorded. The explosion took place 3.8 billions light years from our own planet, and was spotted as part of a survey of the night sky. Though massive, the explosion wasn’t something that could have been seen with the naked eye — say researchers, it was 22,700 times fainter than the most dim object an eye can see.
The faintness was, of course, due to how far away the supernova occurred. Had it happened within a handful of lightyears, it would have been as bright as our sun or thereabouts. The supernova has been named ASASSN-15lh, and it was spotted back in mid-June by the ASASSN telescope network.
The reason for the supernova isn’t known, but Subo Dong, astronomer and lead author, says it likely occurred among superluminous supernovae. The star itself, post-explosion, was likely very large, as well, though analysis revealed it had low hydrogen levels.
One of the study’s co-authors, Todd Thompson, said, “It's weird for massive stars not to have hydrogen. Some stars eject all their hydrogen in explosive events before they die, others lose hydrogen to binary companions." It is, though, possible for massive stars to have low hydrogen levels.