Monday, January 7, 2013


             Lots of neat things happen over our heads in the depths of winter. Like what? you ask. Well, for starters, Earth reached its annual perihelion with the sun on New Year’s Day, when the center of our planet cozied up to within a mere 91.4 million miles of Old Sol. Did’ja notice how unseasonably warm it was? No, probably not here in the Northern Hemisphere. Aphelion, or the greatest distance between star and planet, occurs on July 5th, when the wobble in Earth’s orbit makes us 94.5 million miles distant. Save the date!

            Also under the rubric of “You’ve Already Missed It,” the annual Quadrantid meteor shower reached its peak in the wee hours of the third. Didn’t know about meteor showers other than the Perseids in August?  Gracious, there are six others besides the two mentioned above over the course of the year: the Lyrids in April; the Eta Aquarids in May; the Southern Delta Aquarids in July; the Orionids in October; the Leonids in November; and the Geminids in December. Except for the Quadrantids, meteors emanate from a radiant, or a specific area of the sky, named for a constellation—Lyra, Aquarius, Perseus, Orion, Leo, and Gemini. The Quadrantids’ radiant is Bootes. Perhaps astronomy’s equivalent of taxonomists couldn’t quite stretch to the inane sounding “Bootids.”

            Moving right along to events that are not entirely past, The Globe at Night light-pollution tracking project is calling for citizen-scientist observations of Orion January 3 to 12. This is the first of five opportunities this winter and spring to add your bit to charting where starlight can still be enjoyed. Go to The Globe at Night’s website for information on collecting and submitting data.

What Orion looked like from my front yard last January

            Winter’s cold and clear nighttime skies provide great opportunities for well-bundled-up star watchers. At this time of year, nine of the 25 brightest stars in the sky are visible within or on the perimeter of the asterism known as The Great Winter Circle. Using Orion’s belt as a starting point, it’s easy to find them all. Going out around 10 pm, draw an imaginary line southeast through the three belt stars to the brightest star in the sky, the Dog Star, or Sirius. At a distance of only slightly more than eight light-years from Earth, proximity accounts for his brightness to our eyes. His distinctive blue color indicates that he is hotter than our Sun.

If you lengthen your imaginary line clockwise from Sirius, the next bright object you’ll intersect is Procyon, Sirius’s little brother in Canis Minor. Another near neighbor of Earth, he lies only 11 light-years away. 

The Great Winter Circle (or Hexagon), as presented on Suite 101
(Betelgeuse is over the "n" in "Orion")

           Continuing the clockwise arc, you run into Pollux and Castor, the Twin Stars of Gemini. Sitting at the northernmost point of the circle is golden Capella, the constellation Auriga’s brightest star. Swooshing down and around to the southwest brings you past Jupiter to Aldebaran, the fiery red "eye" of Taurus, the Bull, Orion's prey.

Closing the circle is brilliant blue Rigel, marking one of Orion’s knees (or his right foot, depending on the source). Although from our vantage point Rigel looks a lot like Sirius, the two stars are very different. Rigel, a blue supergiant, is more than 100 times farther away than the Dog Star:  its luminosity is greater than 50,000 of our Suns. In other words, were Rigel as close to Earth as Sirius, it would appear as big as a full moon, and scare us all silly.

Betelgeuse, the ruddy star marking Orion’s shoulder, sits at the center of this "Great Winter Circle.” A red supergiant that has consumed all of the hydrogen at its center, Betelgeuse is nearing the end of his life… but he’ll still outlast all of us.

I find looking up to be a grounding activity. My petty problems and woes shrink away to nearly nothing in the presence of the silence and majesty of the cosmos. Digging in the dirt and staring at the stars brings balance to a life. And, if you’re in a pickle over something and can’t do one, you can do the other until you regain perspective. Works for me, anyway.

Thanks for dropping by.


P.S.—Want to learn more? These three websites will get you on your way: Sea and Sky; Suite 101; and the U.S. Naval Observatory’s SkyGuy’s up-to-the-minute posts on The Sky This Week.