This month look for the star Betelgeuse or Alpha Orionis in the constellation of Orion the Hunter. Betelgeuse is the second brightest star in Orion, which is one of the most recognizable constellations in the winter sky. Betelgeuse is located in the upper left corner and is orangish in color. Betelgeuse and Orion are located high in the southeast on January nights after sunset.

Betelgeuse comes from the Arabic for “hand of the central one”. The central one is a female Arabic character. Feminine names in Orion the hunter are not unusual, one of the constellation’s other bright stars is named Bellatrix, which is also has a female connotation. The light you see from Betelgeuse left the star in the year 1371.

Betelgeuse (the name sounds like beetle juice) is one of the largest stars in our galaxy. If it replaced our sun, its vaporous surface would reach over half way to Jupiter, engulfing the planets Mercury, Venus, Earth, and Mars in the process. That’s 600 times larger than our sun! Betelgeuse is a giant cool red star today; but in its stellar youth was a massive white hot star. Being seven times more massive than the sun, Betelgeuse burned through its main supply of hydrogen faster than the sun. Today, deep in its core, nuclei of helium atoms are fusing into carbon and oxygen. Outside that core is a shell of fusing hydrogen. Since that helium is denser than hydrogen, the helium created by the fusion of hydrogen sinks into the star’s core where it is fused into more carbon and oxygen. The increased heat generated by star’s fusion of hydrogen and helium has puffed up its atmosphere. The expanded atmosphere is a cool red-orange color as a result. However, because of its great size, Betelgeuse over 40,000 times brighter than our sun even though its surface is cooler.

Betelgeuse is so massive that it may eventually fuse the atoms in its core all the way to iron. When it does, the star will face an energy crisis that pales to anything we’ll ever see. That’s because iron is a dead end element and it’s impossible to fuse it into heavier elements to release energy. Since stars need that energy to support their weight, they collapse when their cores contains too much iron. The inward collapse of a massive iron core squeezes subatomic protons and electrons into neutrons and an immense blast of neutrino radiation that will outpace the emission of light from the dense core of the star. Betelgeuse’s blast of neutrino radiation will arrive at earth some 643 years after the core collapses, signally that the star is beginning to exploding as a supernova. When it goes, Betelgeuse will shine as brightly as the crescent moon and be visible in broad daylight.