On January 11th of this year, astronomers at the Keck Observatory in Waimea, Hawaii, were able to detect a supernova in Messier 82 (M82), approximately 11.4 million light-years away from Earth. While 11 million light years seems like a really long distance (don’t get me wrong it is), in terms of cosmic proportions, it’s just right around the corner from us. Messier 82 (M82) is also known as the Cigar Galaxy and in the constellation Ursa Major near the Big Dipper. This is the closest supernova since SN 1987A, which was only 168,000 light years away and could be seen with the unaided eye.
Supernovae occur at the end of a star’s life when its furnace runs out of fuel. Because gravity then overcomes the star’s ability to remain puffed up, there is a violent collapse, followed by an explosion that produces radioactive elements such as nickel and cobalt. Most of the light we see from a supernova is emitted as those radioactive elements decay, so the brightness falls sharply over a period of weeks.
Since most of the atoms in our bodies and just about everything else were made from a supernova, it’s only worthy to point out these rare occurrences whenever we can spot them. The astronomers at the observatory noted that it was mere coincidence they decided to look at Messier 82 when they discovered its death in progress.
Of course, you can’t get too excited about the timing. We see this light 11.4 million years after the explosion happened, because of the time light takes to reach our galaxy. So it was a really special time in M82 11.4 million years ago.