Enjoying a warm cup of Betelgeuse on a cold fall night

Posted Nov. 15, 2011

After all these years I shouldn’t be sur-prised at seeing Orion leap from the east when daylight saving time ends. Yet, there I was, out for a walk before the 10 o’clock news, and the Hunter was in my face. That one-hour fallback propelled Orion up an hour earlier than a week ago, putting his starry personage within sight of people who usually snooze after the news.

For southern hemisphere sky watchers, the rising of Orion must be a welcome sign of the summer season that lies ahead. No doubt Australians associate the constellation with searing heat, swimming outdoors and barbeques. As a northerner, Hunter travels his arc across the sky as the snow piles ever higher and trees pop from cold. I’m sorry, but it’s hard to imagine it any other way.

I don’t know what catches my eye first — the pattern of three stars in his belt or the bright orange twinkle of Betelgeuse. The question often comes up on how to pronounce this star’s name. Officially it’s BET-el-jooz, but I’ve heard delightful variations like ‘beetle-juice’ and even BET-el-goys. The name is a corruption of the Arabic “yad al jauza,” or hand of al jauza, a mysterious female central figure from ancient times. Rigel (RYE-jil) is bluish white compared to Betelgeuse’s ruddy tone and named for the ‘foot’ of al-jauza the Central One.

Though Orion’s brightest star, Rigel did not receive the “alpha” designation you’d expect for a constellation’s brightest star. That honor went to Betelgeuse, which is a few tenths of a magnitude fainter. We know that Betelgeuse is a variable star with an unsteady light very different from our sun, whose rock-steady output we depend on for the continuity of life. It ranges over a full magnitude from 0.2 to 1.2 over a period of six months to many years. Perhaps Betelgeuse was brighter when brightness rankings were first doled out by the ancient Greeks.

Both Rigel and Betelgeuse are fantastically large and brilliant though dimmed, as are all stars, by the equally fantastic distances that separate one from the other. Betelgeuse is the closer at 495 light years, while Rigel beams from 860. Their powerful light gets jiggled by our atmosphere causing each to twinkle like snow crystals in moonlight. A hint of things to come.

Get acquainted with Orion. It’s one of those keystone constellations like the Great Bear. Once learned, the Hunter will help you track down many additional constellations and sights in the winter sky.

King is a photographer at the Duluth (Minn.) News Tribune and amateur astronomer who blogs at astrobob.areavoices.com

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