Invitation From The Milky Way

Cold both creates and locks in some of the most beautiful ice creations of the season, including this array of icicles along the bank of Amity Creek in Duluth yesterday. Photo: Bob King

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.

At left, is an artist's view of how our galaxy would look from above. The photo at right shows the edge-on view looking at it from the side. The sun's position in both views is marked. When we look straight into the galaxy's starry disk, billions of stars stack up to create the milky band of light we call the Milky Way. When we look up through the disk and into the nearly empty space beyond the galaxy, we see only a scattering of stars, no band. Credit: NASA/JPL/Caltech (left); courtesy Ned Wright (right)

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 Milky Way is the faint band of light running through the center of both photos. The Orion half is fainter and less defined than the Cassiopeia portion. Details: 16mm lens at f/2.8, ISO 3200, 30-second exposure. Photos: Bob King

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)  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 red arrows indicate the direction we look into on summer evenings - toward galactic center. The blue arrows on winter evenings - into the outer "suburbs". Other features, including the main arms and the sun's location in the Orion Spur. Credit: NASA/JPL/Caltech/R.Hurt

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.

8 Responses

  1. “After all, do you want to live your life without having known the other half of our home galaxy?”
    No! Dammit. I’m headn’ out tonight! Yep. All of 10 feet from my patio door :0)
    Luckily we’re in the country this week and I just might get a glimpse of those outer suburbs.
    BTW? How cold was it when you were out there getting frostbite. Scary.

  2. Wade

    I live in rural south central South Dakota, and marvel at how bright the stars are on moonless night. The am also able to see, I think it is, the Milky Way running northwest to southeast.

  3. Gary

    I’ve been reading your blogs for a few months now and am learning a great deal about the sky above. I live in Thunder Bay and frequent Duluth so I familiar with your descriptions as to where you are when you’ve taken photos etc.

    This post was particulary helpful to me in explaining the Milky Way in relation to where we are located within it. I will be looking up and understanding what it is I’m seeing.

    Great work and thanks

    Gary Morris

  4. Liz Klawitter

    Hey Bob,
    That’s a beautiful photo of the icicles at Amity Creek. That never gets old, the splendor of water in all it’s forms.

Comments are closed.