[Friends_of_SSASTROS] Notes From The Field - It's Still Winter

[Mike McCabe]

February 18th, 2024; An Evening With Luna and Jupiter

A funny thing tends to happen to us in the winter. As thecold days and nights wear on and the snow refuses to melt, what was once consideredunbearably uncomfortable eventually becomes remarkably tolerable. It’s calledacclimation, and it drives home the point that it’s not only our optics that haveto adjust to get the most out of the conditions. It’s also us. Bundle up, Baby,we’re out there!

Thus it was both on last Friday night and then this Sundaynight. If you just listened to the forecast with its dreadful numbers about temperaturesand wind speeds, you’d likely choose to not go out there. But, bundling up andgetting out there proved that it really wasn’t that bad. For a while,anyway.  

Last night’s plan for a telescopic foray was a simple affair.Put the scope out to cool, then go out to it when all is ready with an eyepiecearrangement that provides the highest usable magnification for the conditions,and take a tour of Jupiter and Luna. No messing around. Pedal to the metal andgo.

Jupiter was O/K. The seeing wasn’t great so the details wereslightly soft, but the sight of Ganymede encroaching upon the western limb atthe end of its transit was spectacular. This far into the evening apparitionfor the King of Planets, it would be several hours before Ganymede’s shadowshowed up on Jov’s disc, and by then it would be deep in my western trees.Jupiter; seen and done for this night.

Moving over to the Moon, the first thing that struck me washow high it was transiting! I guessedaround 80ish degrees as I aimed the scope up to it, and later looked to seethat it was actually 75° at the time. Boy, that thing has some range! There are times in the year whenit’s in the trees all night. According to the extent of my orbital mechanicsexpertise, it all has to do with the tilt of the kilt and the angle of thedangle. Feel free to use that explanation anytime you want.

But I digress. Touring the Moon through a quality telescopeis virtually never a disappointment, and lately I’ve been succumbing to theurge to take pictures through the eyepiece of what I’m seeing. While certainly notthe hi-res masterpieces regularly issued here by the likes of Steve LaFlamme, MattSchricker and Jim Ahola, my cell phone snapshots still provide me with worthy souvenirsfrom an evening’s time at the eyepiece. Come along with me on a brief touralong last night’s terminator!
Prominent in the northern reaches of Earth’s only naturalsatellite, the incredible flat-floored crater Plato was marvelouslyilluminated. The shadows of the southeastern portion of the rim profile can beseen along that area of the floor, as the western rim is brightly highlightedin the sunrise conditions. There are a series of tiny craterlets on that smoothlava floor, but the seeing has to be steady to resolve them in the eyepiece througha small telescope. The conditions weren’t there last night.

Scattered around Plato are a series of mountain ranges andsolo mountains, including the Teneriffes to the W/SW, Mount Pico to the southand the upper reaches of the Luna Alps to the SE. The eastern reaches of MareFrigoris (the sea of cold) lie to the immediate north of Plato, and beyond thatyou get into the Moon’s northern arctic circle region where many interestingfeatures can be found.
Panning south now we comes across that marvelous complexcrater Copernicus, who’s illumination at this point is restricted to somehighlighting of the western terraced wall. Otherwise the interior looks like aninkwell. The area surrounding Copernicus is exceptionally complex and one couldspend hour investigating just that region alone through their telescope.

Look carefully and you’ll note that the intricate andcomplex Copernicus Ray system permeates the entire illuminated region of theimage. Mountain ranges captured include the barely illuminated Carpatus Mountainsjust to the north of Copernicus, while the southern reaches of the lunarApennines trails away from Eratosthenes to the east.

Ever interesting in the view in this region, the darkpyroclastic deposits in the volcanic basalt to the east and southeast ofCopernicus are said to appear that way from a high metal content which couldbecome very important should we ever establish a permanent presence on theMoon. I’ve heard that those areas in particular are heavy in iron, magnesiumand titanium, which lend to the coloration we see.
Our final stop for the evening was in the Clavius region,where so many impact craters can be found that it can be a challenge tonavigate. The nice thing about observing the Moon is that dark adaptation isn’tnecessary, so you can use any resources you want at the eyepiece and it won’taffect your ability to see things.

At 136 miles in diameter, there’s enough going on insideClavius alone to keep an observer busy all night long. Craterlets abound insidethis monster, from the 16 mile wide Clavius D all the way down to tiny pitsjust meters wide. Along the rim there’s the 30ish mile wide duo of Rutherfordto the southeast and Porter to the northeast, and just off the SW rim is thesnowman shaped Blancanus bathed in darkness.

To the south of Clavius lies the incredible 15,000’ deepMoretus (which is hard to tell due to perspective), while to the north at thetop of the frame is Tycho, the source of the most famous ray system on theMoon.

There are literally hundreds if not thousands of otherfeatures left unmentioned in this brief analysis of these three simplesnapshots of our Moon. One of my favorite tools for reference materials on mooninformation is the program Virtual MoonAtlas, which is a free download for PC users. For your phone go to the appstore and pick up either Moon Globefor iPhones or Lunar Map HD forAndroid phones. 

If you like books (which I do), pick up a copy of RobertReeve’s new book Exploring the Moon forone of the most comprehensive tomes ever written on the topic.

I encourage fellow members to share the resources that theyuse and enjoy. It’s what makes a club a community. Please do contribute to thecommunity.

Keep Looking Up!

Mike McCabe


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