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IN SEARCH OF . . . the Blue Planet


Editor's Note: The following is a continuation of the "Astronomy in the Big City" masterpost by longtime GRAAA member Gary Ross.

It is a literary cliche to begin a chapter or book with a description of the weather. However, this account is a scientific report from the field. The autumn of 2018 is wretched in southern Michigan. (Vile also comes to mind.) However, the afternoon of the 3rd of November enjoyed a sharp clearing in the Detroit area after a rainy morning, a mega-bubble of clear air bearing down from some province of Heaven.

The blue of the sky was stunning against remnants of ragged cloud. Ninety degrees away from the pure silver Sun lowering to south-west, one could imagine maximum atmospheric polarisation. This was a sky of minimum Rayleigh scattering, promising the proverbial Good Night.

A serious counter-consideration was that my mother's house, with essentially anti-"horizons," was in Royal Oak about two kilometres north of its central business district. Then too, Royal Oak is pretty much dead nuts in the middle of the Detroit-Windsor conurbation. A lesser man would say, The Devil take it, and spend a disconsolate Saturday night watching back-to-back episodes of The Saint. Whereas this denouement is what ultimately transpired, there was a decent astronomy interlude.

The Man and the Challenge. Am I the only one who remembers the television series of a single season, 1959-60? The evening was providentially clear. In hand was the "eclipse special" 5-cm. refractor of f/11. An arsenal of fine eyepieces, all hand-me-downs, awaited in the big Christmas cookie box roughly, very roughly, converted to scientific employ. It was an opportunity to explore the very outer reach of the formal Solar System.

Neptune had reached opposition on the 7th of September. As is my way, it took about two months for this opportunity to sink in. Why do at opposition what one can put off indefinitely...? In the 2018 edition of the Observer's Handbook, what I call the "book of all knowledge," is a small scale map of Neptune's path in Aquarius by Ian Cameron. At the beginning of November the planet was in retrograde, but was due to begin -- very, very slowly -- "direct" east motion. Of course, note the blue planet is very slow all the time.

This autumn Neptune stands at approximately 7 deg. 30 min. S. Declination, just east of Lambda Aquarii. At opposition in late summer, he was 7.8 magnitude, the two months' interval not a serious disadvantage.

Despite the promise of a pellcid sky, what greeted Man the Observer after astronomical twilight was daunting. Yes, a "challenge". The transparency was five kinds of awful! With naked eye I could see Enif (Epsilon Pegasi) with little difficulty, but lower down, Sadamelik (Alpha Aquarii) was within reach barely. The former is 2.4, the latter, 3.0 mag. With the exception of Fomalhaut just above the southern trees, not a single star was to be seen on this allegedly perfect night. Royal Oak is a jumpin' burg on a Saturday night, so at least some one was having a good time.

The 5-cm. refractor has no finder 'scope. It is its own finder with a superb 24.5 mm. ocular, gift of an old astro-mate, Martin N. Mill. The field of view is approximately 1.25 degrees. Mounted on a camera tripod with one adjustment arm snapped off after I drove over it with the car in the 1980's, the rig can be a bit of a challenge. No, a considerable challenge. Ian Cameron's Neptune plotting is a very small piece of Aquarius, so the Atlas of the Heavens (field ed.) was critical, limiting magnitude 7.75-8.0. None the less, in spite of Neptume's "shining" at ~ 7.9, the whole enterprise was work! (No "go-to" nor "push-to" for this boy.)

Finally -- checking, re-checking the star atlas: I was looking at the out-post of the Solar System with all of 22X. Little doubt I was the only observer in Wayne-Oakland-Macomb-Essex Counties looking at the beautiful methane atmosphere of the Blue Planet that night. Who else would? But was he really blue? To make a good story, one's response would be, "of course." On the other proverbial hand, there is such a thing as honesty, oh, that . . .. No: In a sky essentially charcoal grey, there is no saying that Neptune was blue, too faint at 7.9 mag. I would estimate the field was 38 degrees up, just east of transit. Limiting magnitude in the field, 8.75, little better.

To see the blue of Neptune, if possible, I tried changing to a 9 mm., another Martin gift. It was not to be: With the problem of such a narrow field, time was eaten up as rapidly approaching clouds from the west also ate the southern heavens.

It was a satisfying feeling, however, whilst seeing the blank sky in the wee hours. Got my licks in for observational astronomy in a city-slicker locale not conducive to the outer Solar System. It is not the prize. It is the hunt. More rain came on Sunday, and then more in the mid-week.

- G. M. R. 18th of November, 2018


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