Orion: hero or villain?
Next to the Big Dipper, the Belt of Orion is the most easily recognized asterism (a star pattern usually smaller than a constellation). Visible by 7 p.m. these wintry nights above our eastern horizon, the three belt stars are a unique set of equally bright and equally spaced stars. The rest of Orion is a large rectangle of stars surrounding the belt and easy to spot as well. Since Orion the Hunter is visible from everywhere on the Earth, it figures in the mythologies of many cultures. In fact, historians have found references to Orion on artifacts going back 32,000 years.
In Greek mythology, Orion was a strongman who boasted that with his mighty sword (or club) he could kill all the animals on Earth. This naturally displeased Gaia, the Earth goddess and she sent a scorpion to lay him low, but after succumbing to the poisonous sting, Orion was revived by a snake doctor, Ophiuchus. Those three are now constellations: Ophiuchus the Healer, Serpens draped around him and the zodiac sign, Scorpius. They are located in the summer sky, far from Orion, keeping the antagonists well apart. Had Orion accomplished his evil deed, he would have been the greatest super-villain of all time. Gaia, in spite of her efforts – which saved all the Earth’s animals – does not have a place as a constellation in the sky. She should.
Orion’s corner stars are Betelgeuse, Bellatrix, Saiph and Rigel. The belt stars have names as well: Alnilam, Alnitak and Mintaka but those names just don’t roll off the tongue as smoothly as “Beetle-juice!” or “Bellatrix” (Lestrange), a truly nasty witch in one of the Harry Potter movies. So, yes, there are two actual “movie stars” in Orion, but the most interesting object within his borders is a nebula, a glowing gas cloud named simply the “Great Nebula” and such a dangerous place that not even a sci-fi starship would ever want to venture inside it (at least not without its shields up).
To find the Orion Nebula, also called M42, focus binoculars on the string of four fainter stars dangling from the belt – Orion’s Sword. The “star” in the middle, a decidedly fuzzy patch, is the nebula, but binoculars just hint as to the true beauty of this object. M42 causes more aperture fever among amateur astronomers (a craving for bigger and bigger telescopes) than any other object. The view just gets better and better with larger aperture and M42 is one of the few celestial nebula where colour can be seen.
Since it was first photographed in 1880, the nebula has noticeably changed – points of light have appeared, that is, new stars, among the glowing clouds of gas and dust. M42 is an immense stellar nursery where matter collapses under gravity into dense cores hot enough for nuclear reactions to start. Once the stars turn on, the space around them is cleared by the powerful stellar winds produced. Looking at M42 in a telescope, even at low power, one can see the maelstrom from which these new stars are forming.
In the central region of M42, we find the showpiece, four bright stars called the “Trapezium,” estimated to be only 300,000 years of age (our Sun, a middle-aged star, is 4.6 billion years old). The four stars of the Trapezium are only the easiest to see – there are one to two thousand young stars in the Trapezium Cluster, many hiding among the dust clouds.
All the Trapezium Cluster stars contribute to the light that we see coming from M42. Remarkably, a region only 1.5 light years across, generates enough stellar energy to make the entire Orion Nebula, 20 light years in diameter, glow visibly from a distance of 1,350 light years. Incidentally, the stellar radiation would be deadly to life as we know it. Gaia truly did the entire planet a favour by keeping Orion and his sword in check – well deserving of a constellation of her own, I think.
Clear skies, and enjoy the view!
Amateur astronomer John Hlynialuk checked out M42, the Great Nebula in Orion with an 8-inch refractor telescope, Dec. 19, 2014.