Science | Skywatch with Bill Irwin

By Bill Irwin –

With fall around the corner at last, the smoke has abated, at least out near Horsefly. I have taken my astro gear from the camper, where it was pending evacuation, and reinstalled it in the Bells Lake observatory.

Last night the moon was a slender crescent, probably regaling in the fact that it trumped the sun only four days ago. We saw the partial eclipse on August 21 from our deck with specially filtered telescopes.

The white light view showed the sun’s surface, somewhat unspectacularly, black and white, except for the incredible fine detail in the sunspots. The highly filtered solar scope shows a very narrow section of the sun’s light in the orange/red where a bright line appears in the spectrum.

When electrons are highly excited, they are constantly changing energy levels, absorbing and re-emitting photons. The transitions are very exact, and give rise to the bright line in the sun’s emission.

It’s here that we see the turbulent solar atmosphere and the flares and prominences that rise from the sun’s surface as well as all the turmoil around the spots. During an eclipse, a dragon is supposed to take a big bite out of the sun, so you can think of the spots as teeth marks if you want.

The sun is a busy place and I wouldn’t plan my next vacation there.

Back in the observatory, my first chore is to find the north star and align the telescope’s polar axis to it so it can track the star’s motions. The stars move 15 degrees an hour, which is about the length of the Big dipper’s handle. Over the course of a couple of hours the sky changes significantly, so at the start of an observing session you might want to catch the stars in the south west, before they set.

After a quick alignment of my finder scope, which is a small telescope that rides on the bigger one but has a much wider field of view to aid in locating objects, I checked out the Wild duck cluster in the tail of Aquila, the eagle.

At low magnifications, it appears as a hazy patch, easily visible in binoculars. At higher magnifications, the detail pops out, and the cluster appears in its jewel-like glory. Although there was a considerable technical effort expended to get here, the first impression is aesthetic. The colours, and brightnesses and positions, which we see as figures, are pretty much like listening to music, especially Bach, where the above qualities are replaced with timing, loudness, and timbre.

I quickly checked the Coat hanger, an asterism that looks just like one, to see if it fits the field of my new low power eyepiece. It’s still kind of too big and looks better in the finder.

It is starting to get chilly, but the warm room at the observatory, which is attached to the observing deck, has heat in it, so I go in to check my charts and remove any dew from the eyepieces.

I locate M 15, a globular cluster a short distance from the feet of Pegasus the winged horse. It’s another kind of star cluster, much more densely packed than the Wild Duck or M 11 as it’s known. (Not a secret spy agency, I’m afraid, so you won’t be able to impress your friends.)

It’s getting late and I have things to do tomorrow so I want to see if the Pleiades or the Seven sisters have risen. They look like a miniature big dipper, riding on the shoulders of Taurus the bull. Seeing them rise is a sign that fall is on the way. Tennyson had something to say about them as well, but I’m sure you will trust in the accuracy of Skywatch.

I think I am going to get my big boy out tomorrow night—my 12″ reflector telescope. It definitely gets me closer to the stars although the field is more limited.

As I’m leaving, I see Fomalhaut rising in the south east—a sure sign of fall.

The harvest moon is coming up as well. The ecliptic is the path through the Zodiac that the sun, moon, and planets take. In fall it makes a shallow angle to the east horizon so when the moon is full it rises only 20 minutes later each successive night and appears to hang around for a while, making it a noticeable event. In spring, you don’t think of the full moon as much because it rises about an hour and 20 minutes later each night.

At least we are not thinking about fires all the time now. Feel free to contact me at irwin8sound@gmail.com.

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