Betelgeuse is a star, a very large star, located in our galaxy, the Milky Way. Called a red super-giant, it’s a bright star, the 10th brightest star in the sky, and can be found in the constellation of Orion the Hunter. As a red super-giant, it’s both very red and very big. Betelgeuse is so big, if it replaced our sun it would probably extend to the orbit of Jupiter. In other words, the earth would be smack dab in the middle of it, not a good place to be.
The below image depicts Orion the Hunter, showing the location of Betelgeuse in the constellation. In Orion only Rigel is brighter, but the red color of Betelgeuse makes it easy to spot. Betelgeuse is the reddish star, upper left, while Rigel is the bright star, lower right. In the center are the three stars that make up "Orion's Belt."
Betelgeuse’s distance from us has been estimated at 400-800 light years. The wide range of estimates results from the fact that Betelgeuse is a variable star, meaning it’s brightness can fluctuate significantly over time making it difficult to establish its distance with any accuracy. Some new (2017) technologies, however, using information from a number of ground-based radio telescopes, have concluded Betelgeuse is 724 light years from earth. This conclusion is based on a weighted average of a range between 613 and 881 light years. Using the 724 light years figure, the light we see when we observe Betelgeuse actually left the star in the year 1297 A.D.
(Just to put things into perspective, on September 11 of that year, an army of Scots, led by William Wallace and Andrew Moray, defeated the English in the Battle of Stirling Bridge — a very different kind of 9/11. The 1995 movie “Braveheart” offered an historically inaccurate, but thrilling version of the battle .)
Because Betelgeuse is a red super-giant it’s also a relatively short-lived star. It’s already about 10 million years old, and is expected to live just an additional 100,000 years or so. That’s not long at all when it comes to the life of heavenly bodies. And when red super-giants die, they don’t just fade away quietly. They go out with a bang called a supernova. Indeed, when Betelgeuse finally explodes, the resulting blast will probably be brighter than the full moon. It should be quite a sight.
About two years ago, astronomers noticed a change in Betelgeuse’s brightness that didn’t coincide with its usual variance. Many astronomers thought this change might be a prelude to its ultimate collapse and subsequent supernova blast. Reading about this got me all excited, astronomically speaking, since I’ve long hoped to witness Betelgeuse’s departure. But then a team of astronomers, using the Hubble Space Telescope determined that the dimming of Betelgeuse was caused by an huge amount of hot material ejected into space by the star. It formed a dust cloud that blocked about 25% of the light from the star. The event, which began in late 2019, ceased by April 2020 and Betelgeuse returned to its usual brightness.
From the series of Hubble photos shown below you can observe the effects of the dust cloud. In the middle two photos the star’s brightness has clearly dimmed. The first and fourth photos were taken before the cloud formed and after it dissipated or moved on.
It seems, then, that the star’s temporary dimming had nothing to do with its ultimate demise. Although Dr. Andrea Dupree, who led the Hubble team of researchers, stated that “No one knows what a star does right before it goes supernova, because it’s never been observed. Astronomers have sampled stars maybe a year ahead of them going supernova, but not within days or weeks before it happened.” She then added, “But the chance of the star going supernova anytime soon is pretty small.”
As I said, “Bummer!” I think I was about 10 years old when I first learned of the possibility of a Betelgeuse supernova, and I’ve been waiting patiently ever since. And the weird thing is, because the light from Betelgeuse takes about 700 years to reach us, it might already have happened. Just my luck, if it does happen during the few remaining years of my lifetime, it'll be in the winter months when Orion is less visible.
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