Under Desert Stars   Elen síla lúmenn’ omentielvo

Astronomical Observations Made On 25 August 2019

I don’t often experience clear nights during the Sonoran Desert summer. This is our season for thunderstorms, when moisture pushes into the region from the south and the east, and clouds rise high and white over the desert. The debris clouds left from these storms, whether I see a drop of rain where I live or not, often make stargazing a moot point. Some summers are stormier than others, and for lovers of the “desert monsoon,” a group that includes me, the summer of 2019 has been a disappointment. Storms have been less than frequent where I live, but energetic enough elsewhere to send clouds over my location all the same. The daytime temperatures have often soared to near record highs, and as a result, evenings have also remained uncomfortably warm long after sunset. I have this thing against sweating onto an eyepiece. Those things are enough trouble to keep clean as it is.

The night of August 25^th, 2019, however, was clear and somewhat cooler than those before it. Only a few degrees, actually, but the chance to explore summer constellations was enough to motivate me. The seeing conditions, oddly enough, were predicted to be very good, rather unusual for the season. That news added another bit of motivation. So I decided to fire up the Thermacell mosquito repeller, set up the Old Scope (the 60mm refractor I’ve used since my teens), and see what I could see before heat stroke set in.

Double stars and the moon are the best objects to view with an instrument of the Old Scope’s type and size. Since the moon was not above the horizon while I was out there, double stars made up the majority of my observations on this hot August night. They are particularly rewarding, regardless of the telescope you use, when you work under light-polluted suburban skies. Bright points of light stand out better under such conditions than, say, a ghostly nebula or a distant galaxy. The book that got me started as a serious observer (Field Book of the Skies by William Tyler Olcott) was written at a time when the study of double star systems was cutting-edge astronomy, and most commercially available telescopes were between 60mm and 90mm in size. (Size in this case refers to the aperture or diameter of the lens at the front end of the telescope.) As a result of that combination of then-current interest and available instruments, that book was essentially a guide to double stars, and because I relied on Olcott’s field book, that’s what I observed back then. My interest in double stars has never faded.

It was a quiet night, with no breeze and a clear, calm sky. Normally I find a breeze inconvenient; it flips pages on star atlases and – when strong enough – shakes the telescope.  However, I would have been more forgiving of moving air, any moving air, on such a warm and muggy night. No such luck. It was so quiet I could hear the Thermacell unit softly hissing away as it heated the repellent-soaked pad that drove off mosquitoes. I rely on that device during mosquito season. Without it sending its chemical signals that baffle and repel the little blood-suckers, I’d need long pants and a long-sleeved shirt. I’d be seriously over-dressed for a night during which the temperature was likely to remain above 90°F, which was the case this time.

It was, in fact, rather too warm for my liking, regardless of manner of dress, and I honestly wondered why I was bothering. And then I put gamma Delphinus in the eyepiece.

This star is in a summer constellation that actually looks a bit like its name – a dolphin. Both components of the double star were easy to see, and gamma Delphinus was worth the sweat. When observing double stars, the brightest of the pair (assuming a difference) is generally labeled “A” and is referred to as primary, while the secondary is usually labeled “B.” It can actually get a lot more complicated than that – but not this time. The two stars in this case are quite close together, and needed a fair bit of magnification to split them (separate to them completely). At that magnification I was also able to see their colors. The primary (A) star was pale yellow, and the companion (B) was an equally quiet shade of blue. The difference in magnitude was subtle, about half a magnitude, but was visible. The sight of these two softly colored gems against the dark sky made me glad I’d bothered.

Another star on my list was a jewel of the Dolphin as well. Alpha Delphinus has a companion too faint for the Old Scope to pick up, but when I was a teenager I very likely didn’t realize this, and would have looked. I’ve recently been revisiting stars that I would have looked at back then, using the same old telescope as before, so since it was on the list I would have used then, I looked at it on this night. Alpha Delphinus was another gem, this one bright and white with a hint of blue in it. It’s a simple sort of beauty, the light of a distant star, and irresistible.

The hot and sweaty night grew older but no cooler, and the stars moved slowly east to west overhead. The planets Jupiter and Saturn were bright and easy to find over the roof of the house, but the heat shimmer from the roof made observing them a waste of time. They looked for all the world as if they were under water.

While star hopping, I found myself in the vicinity of an object labeled on the charts as M 15, a dense gathering of stars called a globular star cluster. I’ve seen this thing with a larger telescope and been amazed by the sight. What amazed me this night, using the Old Scope, was that I could see it at all. The gray patch of light that seemed to fade gradually into the night sky around it may not have been visually impressive, but seeing it with such a small telescope in a relatively bright sky was a pleasant surprise. You just never know, so you might as well try. And doesn’t that just sound like a life lesson?

I split several double stars in Corona Borealis (the Northern Crown), Pegasus (the Winged Horse of myth), and Andromeda. Of them all, the most noteworthy was gamma Andromedae. It was a tight pair of stars, as viewed with the Old Scope, and displayed more conspicuous colors than gamma Delphinus. The brighter of the two, in this case, was a clear golden hue; its companion was a gleaming blue. I keep calling these stars gemlike, but in truth, there are no gems on this Earth of ours that can compare. If you ever have the opportunity to look at such a sight through a telescope, be sure to take it. I think you will agree with me on the subject of the beauty to be seen in starlight.