I felt the true meaning of cold last night when there wasn’t enough strength in my fingers to turn a thumbscrew while trying to disassemble the telescope. I shook my arms like crazy until a meager bit of warmth returned, and I was able to tease and prod the screw loose. On the way home, the car heat was set to full blast. I steered with my inner arms while my fingers clung to the heating vents for warmth.
Such is the price one pays for standing under a nice, dark winter sky away from city lights. Only when you’re away from the city can you appreciate the subtle glow of the winter Milky Way. It’s really divided into two large sections as seen from mid-northern latitudes. There’s the Cassiopeia half, which stands straight up from the northwestern horizon. On the opposite side of the sky, rising higher as the night goes by, is the Orion half.
First, a couple of definitions. The Milky Way is the name given both to our galaxy and the milky band of starlight we see at night. We can only ever see part of the 360-degree circular band of the Milky Way galaxy, because it’s cut off by the horizon. And although our galaxy is a magnificent barred spiral some 100,000 light years across, we’re forever stuck in the middle of its flattened disk. We can’t jump in a rocket ship, travel at light speed and hover above the galactic plane to marvel at the Milky Way’s radiant central bulge of ancient stars or truly appreciate the symmetry of its spiral arms dotted with pink clouds of glowing gas. Nope. Located as we are inside the galaxy, when we look through its disk on a dark night, we see stars stacked upon stars stacked upon stars – so many that they blend together into a thick band of soft light tied like a ribbon around the sky.
The Cassiopeia half in the northwestern sky is definitely the brighter, easier portion of the wintertime Milky Way. It shows lots of texture created by numerous star clouds and thick seams of dark, unlit gas called dark nebulae, too. Turning around to look at Orion, I’m reminded of the wispy curls of steam rising from Lake Superior on subzero mornings. The band runs from just left of Sirius (star at bottom in the photo above)Â and grazes the east side of Orion before ascending into Gemini and Auriga. The portion from Orion southward is soft, faint and nearly featureless. Even though the starry band narrows in Auriga the Charioteer, it’s a bit brighter and stands out better. Though the band looks like little more than mist, it’s comprised of billions of stars, mostly faint, distant ones. Binoculars and telescopes resolve it into individual stars and clusters, and give us a flavor of its true nature.
The winter Milky Way doesn’t compare to the brightness of the summertime version. This has to do in part because of where the sun is located in the galaxy, some 30,000 light years away from the center, more than halfway to the outside edge. Yeah, we’re in the burbs. During winter nights, our planet faces the “outer suburbs” and rural fringe of the galaxy, where the stars thin out. In summer, we face inward and gaze across many more light years of stars and star clouds toward the center. Their combined light contributes to a much brighter Milky Way arch on summer evenings.
Few sky watchers have seen the winter Milky Way, either because of the cold or the effort required to find dark skies. We’re more likely to have caught a glimpse of the summer version, when the nights are conducive to walking or camping. If you’ve never had the pleasure of seeing the wispy, wintertime Milky Way flow past star-spangled Orion, don’t pass up the opportunity to see it . After all, do you want to live your life without having known the other half of our home galaxy?
The best time for viewing the Milky Way is when the moon is out of the sky from about 7 until 11 p.m. now through February 4 and again from 8 till 10 p.m. Feb. 19 through March 6. My recommendation? Put on every layer you own and get outta Dodge.