THE star Betelgeuse is causing great excitement in the astronomical world as it is clearly getting dimmer.

Usually the 11th brightest star in the sky, but now outside the top 20 in terms of brightness, Betelgeuse is easily visible to the naked eye in the constellation of Orion.

It is also known as Alpha Orionis which is certainly much classier than Betelgeuse. The latter originally derives from the Arabic for armpit of Orion – in the imagination of those who first mapped the stars into constellations, Betelgeuse formed either the hand or oxter of Orion the Hunter, a figure from Greek mythology. In technical terms, Betelgeuse is a red supergiant of spectral type M1-2.

It is about 10 million years old and has evolved rapidly because of its sheer mass. If it were to relocate to the position of our Sun it would engulf every planet to the other side of Jupiter – and it is about 700 light years from Earth, meaning that we are now seeing Betelgeuse as it was when the Declaration of Arbroath was made.

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IT has long been known that Betelgeuse is a semi-regular variable star, meaning that its brightness can increase but also decrease. Indeed it has the largest range of magnitude of any major star. At present, the dimming phenomenon is visible even to the naked eye – Betelgeuse is around two-thirds of its normal brightness and its normal reddish hue is even more pronounced.

Several astronomers have theorised that the current dimming is all just part of a natural cycle for the star, but others are noting the greater variation in magnitude and speculating that the end is nigh for Betelgeuse.

National Geographic reported in November: “Decades of photometric data show that Betelgeuse brightens and dims in cycles, with one notable cycle vacillating on a roughly six-year time scale and another rising and falling every 425 days or so.”

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Yet the current dimming is markedly greater and definitely different. The European Southern Observatory’s Very Large Telescope (VLT), captured how much the star has dimmed over the last year and they also noticed that Betelgeuse has somehow changed its shape.


AS it is in its Red Giant phase already, Betelgeuse is doomed to expand and then collapse before exploding in a supernova, which will then leave behind a neutron star or a black hole, though the former is much more likely than the latter.

If astronomers and astrophysicists are correct the supernova won’t occur for at least 100,000 years, by which time humankind will probably be either dead from climate change or nuclear war or some sort of virus, or we’ll be living on other planets and be perfectly safe anyway.

Reports and rumours have speculated that everything from gamma rays or ultraviolet radiation will head our way when the supernova happens, but even if Betelgeuse creates the greatest supernova ever, we’re still far too far away to be affected.

The largest supernova on record took place in 2006, when a star 100 to 200 times more massive than our own sun went nova. It was in a galaxy 240 million light years from our own solar system and it hardly made an impression, with only the very biggest telescopes able to see it.


THEORETICALLY, it could go nova at any time, and there’s great deal of wishful thinking going on by astronomers because no living person has seen the supernova of a red giant star close enough for us to observe it.

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Andy Howell, an astronomer who studies supernovas at the Las Cumbres Observatory and the University of California at Santa Barbara, told NBC News of the excitement of possibly witnessing a supergiant red star like Betelgeuse going nova, especially as in space terms it is relatively close to Earth.

Howell said: “It would be astounding. No person alive today will have seen anything so glorious as what will happen when Betelgeuse blows up. You could see it in the daytime, it would cast shadows at night, everyone in the world who could see Orion would be able to see it.

“It would transform people’s fascination with the night sky.”

One of the first people to spot the dimming was Professor Edward Guinan, astronomy professor at Villanova University in Pennsylvania. He said: “We are keeping a good eye on it. The star is going to blow up. It has no other choice in physics. I just don’t think it is now. But I’m becoming less and less certain of that.”


BETELGEUSE is part of one of the most distinctive constellations in the night sky in winter. Viewed from Scotland on a clear night, Orion is easily spotted in the southern half of the sky because of its “belt” of three stars. In the quadrangle of stars around the belt, Betelgeuse is the star to the top left of the belt as we look at it.

Take a line from Betelgeuse through the middle star of the belt and you come to Rigel, also called Beta Orionis, which is one of the brightest stars in the sky and is certainly not getting dimmer. It is a blue white giant star and is the sixth brightest star in the sky.


IN a roundabout manner. Michael McDowell, one of the writers of the 1988 madcap comedy horror movie directed by Tim Burton, said the star’s name inspired the character played by Michael Keaton. He is actually called Betelgeuse in the film, but Beetlejuice is an accepted pronunciation.