Will Betelgeuse become a second sun?
Short answer: no. If you’ve read or heard that the star Belelgeuse might explode in a few weeks or a few months – that it will temporarily add a second sun to Earth’s sky and somehow also possibly prove the world will end in 2012 (to which we can only say, “huh?”) – you might want to find more reliable sources. While it’s possible that Betelgeuse will explode in our lifetimes, it isn’t likely. Someday, Betelgeuse will become a supernova. This event is just as likely to happen thousands or millions of years from now as tomorrow.
What’s more, the best minds among astrophysicists assure us that even when Betelgeuse does blow up, our planet Earth is too far away for this explosion to destroy life on Earth. They say we’d have to be within 50 light-years of a supernova for it to harm us. Betelgeuse is nearly 10 times this distance, so Betelgeuse will not destroy life on Earth. But astronomers will be extremely thrilled to have a relatively nearby supernova to study, and the rest of us will be treated to an amazingly beautiful sight in the night sky – a very, very, very bright star.
Betelgeuse lies some 430 light-years from Earth. Yet it’s already one of the brightest stars in Earth’s sky. The reason is that Betelgeuse is a supergiant star. It is intrinsically very brilliant.
Such brilliance comes at a price, however. Betelgeuse is one of the most famous stars in the sky because it’s due to explode someday. Betelgeuse’s enormous energy requires that the fuel be expended quickly (relatively speaking), and in fact Betelgeuse is now near the end of its lifetime. Someday soon (astronomically speaking), it will run out of fuel, collapse under its own weight, and then rebound in a spectacular supernova explosion. When this happens – which could be tomorrow or a million years in the future – Betelgeuse will brighten enormously for a few weeks or months, perhaps as bright as the full moon and visible in broad daylight.
Fortunately for us, it appears that there will be few, if any, adverse affects to Earth when Betelgeuse goes supernova.
If Betelgeuse were side by side with our sun, you’d find it 10,000 times brighter than the sun in visible light. It might be surprising then to learn that the surface temperature of Betelgeuse is only about 6,000 degrees F (3,600K) in contrast to the sun’s 10,000 degrees F.
In terms of mass, Betelgeuse is thought to be about 15 times the mass of the sun, but 600 times wider and more than 200 million times its volume! When you consider its size, as well as the infrared and other radiations it pumps out, Betelgeuse probably outshines our sun by at least 50,000 times.
How to see it
At mid-northern latitudes around the first of every year, Betelgeuse rises around sunset. The star is very well placed for viewing in southeast to south on February evenings.
By the beginning of March, this star is due south in early evening. By mid-May, it can be glimpsed briefly in the west after sunset. Betelgeuse is traveling behind the sun in early summer, but it returns to the east before dawn by about mid-July.
Betelgeuse – in the famous constellation Orion – is easy to spot. See our sky chart to learn the pattern of the constellation Orion the Hunter. Orion itself is noticeable for the short, straight row of three medium-bright stars in its mid-section. Betelgeuse is in the upper left corner of the large rectangle forming Orion.
The star Betelgeuse has a distinctive color: somber orange-red. It’s ideal for convincing non-believers that stars do, in fact, come in colors.
Stars designated as Alpha are typically brightest in their constellations. But Betelgeuse is Alpha Orionis, despite the fact that it’s fainter than Orion’s other bright star, Rigel. Betelgeuse is the 10th brightest star in the sky overall, and it’s the 7th brightest star visible from most of the U.S., Canada, Europe and the majority of the northern hemisphere.
History and myth
Remember the movie Beetlejuice? This star’s name is similar.
The proper names of many bright stars are Arabic in origin. This fact reflects the dominance of Arabic astronomers and astrologers during Europe’s Dark Ages. The name Betelgeuse apparently is derived from an Arabic phrase that is usually translated as The Armpit of the Giant. Of course the Giant refers to Orion, but – rather than an armpit – some authors see Betelgeuse as representing a hand or sometimes a shoulder. While it is not entirely clear what the name means, in any event, Betelgeuse marks the right shoulder of Orion in many old star maps.
In the ancient myths, Orion is most often associated with a giant, a warrior, a hunter, a god or some other anthropomorphic or animal figure, so it is not surprising that most depictions of Betelgeuse have an anatomical connection. The Sanskrit name signified an arm, too, for example, although it likely was really the leg of a stag. In parts of Brazil Betelgeuse was seen as the hind leg of a cayman (crocodilian) or the foreleg of a turtle. On the other hand, in ancient Japan, Betelgeuse was considered to be part of the rim of a ceremonial drum. In Peru, it was one of four vultures about the devour a criminal.
So come to know Betelgeuse. And don’t worry. The chances of it exploding in our lifetimes are … well, astronomically small. Even if it did explode, it would not add a second sun to Earth’s sky. It would not prove the world will end in 2012. It would be, most likely, a wonderful natural event that we’d all tell our grandchildren about.
The position of Betelgeuse is RA 05h 55m 10.3053s, dec +07° 24′ 25.4″.