If you go out at night in the summer and look towards the north, you will see a recognisable constellation: Orion. Some people know it as ‘The Pot’. Just below the pot and to the right you will notice a very bright, orange-red star, called Betelgeuse.
Betelgeuse is the second brightest star in the Orion constellation, and is usually listed as one of the 10 brightest stars in the night sky. It is a red supergiant, around 500 times bigger than our sun, and lies about 642 light years away from us.
In 1995, Hubble became the first instrument to directly image the surface of another sun – that being Betelgeuse.
Recently something very odd has been happening with Betelgeuse. Starting in October 2019, Betelgeuse began to dim noticeably, and by January 2020 its brightness had dropped from magnitude 0.5 to 1.5. Once one of the top 10 brightest stars in the sky, this has now fallen to 21st place.
Unlike most stars, which burn hydrogen, giants and supergiants have exhausted their hydrogen supply and are starting to burn heavier elements such as helium and carbon. Once these fuels are used up, the giants collapse into their core and trigger a massive explosion known as a supernova. Could this be what is happening to Betelgeuse?
If this is correct, what can we expect? You might walk outside in broad daylight, look up at the sky, and see a luminous orb as bright as a full moon. Only it wouldn’t be the moon. You’d be seeing the light from Betelgeuse going supernova.
You could be standing in the middle of one of the biggest cities in the world at night, and the supernova would still be clearly visible. In the countryside at night, you could probably read a book by the light from the supernova.
What is even more amazing is that you will probably see this supernova in the sky for a year or more before it dies away. Even with all this drama in the heavens, we would be safe. Betelgeuse is so far away that radiation from the explosion would be harmless by the time it got here.
But will this happen soon? We don’t really know. Scientists think that the current dimming may not be related to it going supernova at all. It has been dimming a brightening for most of recorded history, although not to the extent it is dimming now. Some astronomers believe that the change in brightness could be due to some sort of eruption of gas or dust, or changes in the star’s surface brightness.
Many believe that the dimming cycle will end soon and Betelgeuse will return to its former glory.
So will Betelgeuse go supernova? Yes it will – bnt probably not in our lifetime. This event is predicted to happen sometime over the next few hundred thousand years.
We have to remember that predicting supernovae is still an inexact science, so there is still a possibility, however remote, that Betelgeuse’s fiery demise could happen sooner. Or, to be more exact, it happened 642 years ago and the light from it is about to reach the Earth.
So next time you are looking at the stars, take a look at Betelgeuse. You never know whether it is the last time you will ever see that star in the night skies again!