Normally clouds are anathema to astronomers, and the thought of clouds will send the dedicated meteor shower aficionado into a depression. But the other night (August 12-13, 2010) I welcomed them as honored and interesting guests. I read recently that people of ancient India spoke of shining nature spirits who they sometimes identified as “cloud horses” rolling majestically across the sky. Not so much that they look like horses, but that they are free-spirited mystical beings in constant motion. Some graze slowly. Some race by. Some are calm and beautiful. Some are dark and stormy. We’ve all seen puppies, bunnies and ducks, but I suppose it is not such a stretch to see clouds as some form of rapidly evolving living beings, and perhaps horses are a good analogy.

With clear but light polluted skies and a pair of sleepy eyes, I missed the best of the Perseids this year. But for about 10 minutes or so of the time I was observing from my backyard, I was treated to a cloud horse. It slowly rolled across the northern sky, small and solitary yet constantly changing as it went. It never actually looked like a horse, but little imagination was needed to liken it to a cloud of dust following a distant horse racing across the desert. (Thankfully such sights are not completely gone today, but the “horse” is more likely to have wheels instead of hooves and be made of steel rather than flesh). I could almost hear the opening to “The Dance of the Knights” from Romeo and Juliet by Prokofiev (listen to it on Youtube or elsewhere and you will know what I mean.)

My cloud horse started off more or less round, and about the size of my fist held at arm’s length. There were a few other clouds in the sky, but toward the northeast this one was solitary, almost reminiscent of the image of a white stallion standing majestically at the precipice of a cliff, with mane flowing in the wind. It drifted slowly from West to East, developed a cleft and then separated into two cloudlets, each becoming cloud changelings on their own. Distracted for a few minutes, I turned back and it was finally gone, which coincidentally was approximately as it crossed Perseus.

What made this cloud, a good example of “fair weather cumulus,” so noticeable was that it was isolated from other clouds, passing through a relatively dark sky, and most importantly, lit by the city lights of Denver. Usually at night most people barely even notice clouds, but this one fairly demanded attention. The accompanying image gives an idea of what it looked like, but it is not the cloud horse I actually observed. In fact it is of a similar formation photographed by Petr Kratochvil and generously released to the public domain. I have cropped it and adjusted contrast a bit to make it appear more like what I saw last night.

Jupiter was a beacon, almost Venus-like in the southeastern sky, but largely out of my view. I saw a number of non-meteoritic flashes of light, which I suspect were Jupiter occasionally passing between leaves, and its light refracting through the edges of my glasses. Either that or else distant “heat lightning” to the South, which I doubt. And then there were familiar signs of the coming fall, the fuzzy Pleiades and a surprisingly bright Capella. In Denver, the late night air was cool and crisp, making that all the more real.

As far as the meteor shower went, I saw what I would estimate to be a reasonably good display at perhaps the rate of 10 Perseids per hour. Considering that I stayed in town (within the city limits of Denver) and had but a small patch of sky to view, I think a rate of 10 per hour is pretty impressive. I have several large trees in my back (South facing) yard, which when in full leaf, block at least 80 percent of the sky. (Meteor watching there is much better in the Winter!) My front yard has a better view but more lights. The back was completely free of lights until a neighbor turned on a light in his house that was astonishing bright and distracting. Unfortunately no fireballs or noticeable colors, but considering the impediments to observing, it went well.

It wasn’t just cloud horses and meteors, either. There were other things to notice in the relative quiet. At one point I saw a fast-moving, high-flying and insanely flashing airplane, helping me understand how some people could mistake such things for alien spacecraft. That aerial sparkler was silent, but the night was anything but. Aside from the sounds of traffic from two major streets (Monaco and Evans) a few blocks away, not-so-distant sirens and barking dogs, there were other sounds. Occasionally I heard rustlings in the trees that I am confident were from critters of some sort — likely the neighborhood raccoons. But it was the sound of crickets that made the greatest impression. They were scattered around the backyard and all singing at nearly the same rate. But there was a very slight difference, maybe because it was a fraction of a degree cooler under the bushes than near the house. In any event, the very slight difference in frequency gave the singing a kind of harmonic effect, slowly bringing them in and out of sequence every minute or so.

Now I’m looking forward to the Geminids in December, but oh how I will miss the crickets.