Orion's back! Few sights are as welcome as the three stars of his Belt glinting between bare branches. Throw in a bright moon to light up the snow, and you've got the perfect excuse for a winter evening stroll. On moonless nights bring along binoculars and scan the Belt. The region is rich in stars just below the naked-eye limit and makes a sumptuous sight.
Since the Belt is familiar and bright, it makes an ideal jumping-off place to explore the rest of the hunter's anatomy. Conveniently, the trio is located midway between Orion's two brightest stars — rosy Betelgeuse in his right shoulder and twinkly-white Rigel in his left foot. Betelgeuse is a red supergiant star about 700 times larger than the sun located 642 light years away. The light that beams from the behemoth tonight departed in the Late Middle Ages on its epic journey to Earth.
Rigel is a blue supergiant star "only" 75 times as large and about 860 light years away. Seventh brightest in the night sky its true brilliance is 120,000 times solar, a degree of radiance difficult to comprehend. Let's just say that if Rigel were put in place of the sun it would fry every living thing on the surface of the Earth.
Two fingers held together at arm's length (4°) below the Belt you'll spy three fainter stars arranged in a vertical line. That's Orion's Sword and the most popular amateur astronomer hangout in the wintertime sky. Smack in the middle of the Sword is a fuzzy-looking star. Binoculars will reveal a tuft of haze in the shape of an inverted-flower form. This is the Orion Nebula, one of the closest and brightest star-making factories to Earth.
A 6-inch telescope will show amazing textures here along with blobs of tar-dark nebulosity, hints of color and the spectacular quadruple star called the Trapezium, responsible for illuminating the cloud. The quartet was born only 300,000 years ago when gravity compacted dust and gas and kindled it into suns. There are currently about a thousand newborn stars hidden within the nebula's folds and more on the way. From a dark sky the Orion Nebula is of the most beautiful sights in the universe. I return to look at it again and again every fall and winter.
Just a few degrees below and left of the Sword we arrive at Saiph, the star that marks the knee of Orion. Its name comes from the Arabic "saif al jabbar" which means sword of the giant. Like Rigel and Betelgeuse, Saiph is also a supergiant star.
We often hear that Betelgeuse will self-destruct as a supernova sometime in the relatively near future. The same fate awaits Rigel and Saiph. A supergiant star typically does not go gentle into that good night at the end of its life. Once it's used up its nuclear fuel and the star's internal "furnace" has shut down, it can't fight back against the inexorable pull of gravity. The massive gasbag implodes and then rebounds in a catastrophic supernova explosion visible across millions of light years.
We return now to Betelgeuse in Orion's shoulder and inch our way north along a faint lattice stars that represents his upraised club. Nowadays, hunters rarely carry a club, but before bullets were invented it was an effective tool. Homer in the Odyssey describes the club as being made of solid bronze. Because the club's stars are on the faint side at 4th and 5th magnitude the best time to see them is when the moon is out of the sky. They add an element of action, even fearsomeness to the Orion figure and are well worth the effort to see.
From the club we turn west (right) and focus on a compact triangle of stars that represents the hunter's head. The brightest star, Meissa, is easy to spot at magnitude 3 with the other two a magnitude fainter. For the head of a famous hunter it's awfully small, but looking at a star map its plain to see there wasn't much to work with in this sparse region. Be sure to point binoculars at the little triangle. It's not just a random arrangement but a true star cluster called Collinder 69 which features a miniature version of Orion's Belt in a vertical row.
Below and right of Orion's head we arrive at the final star that forms the familiar, boxy outline of the constellation — Bellatrix, located in the hunter's left shoulder. The name comes from the Latin word for female warrior. Bellatrix is a giant star about six times the diameter of the sun and the third brightest star in Orion. From Bellatrix we launch to the west and arrive at a trickle of stars that form the curved arc of his shield. In some depictions the shield is replaced with a lion's pelt.
Like the club, the shield is made up of generally fainter stars with the exception of its brightest, called Pi (𝜋) 3, which shines at 3rd magnitude. If you like pi you'll find a lot of it here. Most of the shield stars are neatly lined up and of similar brightness so they all received the same "pi" designation with an individual number. Stars in a constellation are labeled according to brightness using the letters of the Greek alphabet starting with alpha (usually the brightest) followed by beta, gamma and so on through omega.
With club in one hand and shield in another, Orion forever stands poised to fight Taurus the Bull, who glares from above, horns aimed and ready.
"Astro" Bob King is a freelance writer for the Duluth News Tribune. Read more of his work at duluthnewstribune.com/astrobob.
