Orion: hero or vil­lain?

Wiarton Echo - - NEWS - John Hly­nialuk

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!

Photo by John Hly­nialuk

Am­a­teur as­tronomer John Hly­nialuk checked out M42, the Great Neb­ula in Orion with an 8-inch re­frac­tor te­le­scope, Dec. 19, 2014.

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