There was a time, about 180 years ago, when Eta Carinae became the second-brightest star in the southern sky. Observed around 1843 in the constellation of Carina (the Keel), the supermassive star experienced an enormous celestial outburst, the cause of which has long since been a mystery. Occurring between 1837 and 1858, the event became known as the ‘Great Eruption’, causing the star to become ever brighter until it eventually faded to the point it could no longer be seen by the naked eye. Intriguingly, it released as much visible light as a supernova explosion, but unlike novae and supernovae, the brightness remained for some time. The star also didn’t die.
Over the years we’ve come to learn more about Eta Carinae, the star once known as Eta Argus. Having brought us tantalisingly close to a naked-eye witnessing of a supernova within the Milky Way for the first time since 1604, we know that it’s a stellar system containing at least two stars. We also know that it’s some 7,500 light years away from the Sun and that it’s surrounded by a cloud of dust and gas called the Homunculus Nebula, which was ejected from the star following the outburst in 1843. Astronomers believe it’s likely to be the next star in our galaxy to explode as a supernova because it’s thought to be approaching the end of its life. If it does, it promises to be some sight.