Observing conditions during yesterday’s lunar eclipse were excellent here in Gothenburg. Clear blue skies, still 24 degrees C at midnight this extraordinary hot Swedish summer. I decided to observe the eclipse from a hillside in Slottsskogen, the city’s largest park. And I was not alone. Apparently the heads-up for the eclipse had reached many Swedes, and it turned into a social event with people crowding all the park sites with a good view to the southeast.
The moon rose at 21:40 (CEST). Around ten o’clock people around me started to get anxious and I had to reassure them that they hadn’t missed the event, and that they just needed to be patient. As luck had it ISS happened to pass by, which drew some cheers from the crowd and probably stopped some from turning back home.
And then there it was. Occupied pointing it out to everyone I didn’t check the exact time, but around half eleven a very faint dark moon had appeared a couple of degrees above the southeastern horizon. And it soon got better. At eleven the reddish hue of the blood moon was obvious.
I had planned to make some sketches with my 7×45 binos, but it was difficult to focus with people moving about, asking questions, borrowing the binos and so on. Below are some of the resulting, quite rough sketches.
All in all this was a memorable evening. The weather was perfect, the moon at it best, and on top of that a cheerful crowd, many of them experiencing a lunar eclipse for the first time.
Lunar domes Mons Gruithuisen Delta and Gamma can be found in the moon’s northwestern quadrant, between prominent crater Mairan, and not so prominent Gruithuisen (neither of which are captured in this sketch). The two domes are the features in the center of the sketch, with Gruithuisen Delta to the left and Gruithuisen Gamma, which has been said to resemble an upturned bathtub, to the right.
During the observation my eye was drawn to a small feature just north of Gamma. It actually consists of two small adjacent craters, but with the sun angle at the time of the observation, they looked like one crater with a very thin and shiny white ‘bridge’ traversing the darkness of the crater’s interior. The view was truly mesmerizing, especially as the feature after some time seemed to detach itself from the crater wall. There is of course the infamous O’Neill’s bridge on the western shore of Mare Crisium, and it struck me how easy it is to be fooled by the moon’s ever changing lightning conditions.
At first glance nr 36 on the Lunar 100 list — the Grimaldi Basin — seems to be an easy catch. Its quite big and easy to spot in the lunar landscape. It is even just about visible naked eye. But the basin as such is not enough to tick off L 36 — you need to trace both its “outer and inner rings”, and that is a more demanding task.
Preparing for my observation I consulted a number of maps and images to make sure that I had a pretty good idea of where to look for traces of the rings. Still, and at the telescope, the outer ring was far from obvious. Some parts stood out alright, especially on the eastern side, others were more difficult.
Covering such a large area it took me almost an hour to complete the sketch. Even so some parts were sketched rather haphazardly, and especially the southern parts could have used more attention.
One evening last week, while inspecting the terminator, I came across the Encke crater. The illumination was favorable and I decided to give it at go at the sketching pad. Starting out my eyes were soon drawn to a spiky pattern closer to the terminator. I have recently bought a copy of Harold Hill’s wonderful A Portfolio of Lunar Drawings, and I immediately recognized the spikes from one of his drawings(p. 70-71). I decide to extend the range of the sketch and to try to render both Encke and the shadows cast by the remnants of Maestlin R.
Maestlin R draws it’s name from Maestlin, a small and rather unassuming crater just to the north of it (bottom right in sketch). The spikes are created by a series of peaks in the degraded crater wall and cast on the smooth mare. At the time of the sketch the western wall of Maestlin R shone brilliant white, creating a striking contrast.
Encke is a rather large, polygonal and floor-fractured crater. Several ridges were seen on the floor, most notably a ridge traversing the floor from north to south.
Mike Wirth have imaged the area under similar illumination. The image can be found on LPOD.
On 10 February 2014 I made a sketch of lunar crater Gassendi. At the time I was just starting out in lunar observing and this was my first sketch of a major lunar crater. It goes without saying that I found the task quite challenging. Yesterday, and almost two years down the road, I had the opportunity to make a new sketch of Gassendi.
At both occasions Gassendi was sketched under similar (but not identical) lighting conditions and with good seeing (4/5). This means that the differences between the two sketches are due not to atmospheric conditions or the sun angle, but rather to my experience as a lunar observer.
After many years of deep sky observing I know from experience that the hours spent at the telescope slowly increases your ability to see faint details and to observe low contrast object. But when I started out doing lunar observations I would never have guessed, that the hours spent gazing at comparably bright and contrasty lunar features, would have a similar effect. Obviously they did. My sketching techniques has improved somewhat (still a long way to go), the precision in the depiction is better, but most notably I am happy to see that my attention to detail have increased.
I will try to return to Gassendi in the years to come. Hopefully the next sketch will show some further improvements.
Lunar features are always challenging to sketch, but some are more difficult than others. Still very much a beginner, I find highland targets close to the limb almost impossible to do justice. Or rather: I can sketch them, but the results looks like crap. As this sketch of Inghirami Valley.
The valley is adjacent to Inghirami crater (to the left in sketch) and can be found close to the moon’s southwestern limb. It is radial to the Orientale Basin, and it was formed by ejecta from the Orientale impact. At the time of the sketch it had a very squarish outline, giving the impression of at lunar airfield (without the air).
There are two additional valleys in the area, both associated with the Orientale impact: Baade Valley, just south of the Inghiram Valley and hinted at in the sketch, and the Bouvard Valley, slightly to the west.
Bailly is a libration object located close to the southwestern limb of the moon. Traditionally it has been recognized as the largest crater on the nearside of the moon, but today it seems to have been upgraded to a lunar basin (without the defining maria).
The short description in Charles Wood’s Lunar 100 list states that it is a “barely discernible basin”, and that might be so, but as a crater I found it both rewarding and quite straightforward. My observations was done under a 13.7 days old moon, which, in combination with the libration at the time, positioned the terminator on top of Bailly’s far wall, thus creating a nice framing of the view.
At first I was a bit confused by the shadow on the crater floor in front of the far wall — it seemed to be on the wrong side of the wall. My best guess is that this is an effect either of the moon’s curvature and the closeness to the limb, or of a convex shape of the floor as such. The effect is beautifully illustrated in an image captured under similar lighting conditions by Damian Perch (scroll down to B).
The three parallel strokes above Bailly B (the large floor crater to the left in the sketch) also got me wondering. I have a wage memory of putting them there intentionally, but now a week later they seem odd, to say the least. Again comparing with Peach’s image, I can’t see any structures that might correspond to my strokes. Better just forget about them.
Anyway, I found Bailly a very rewarding object, and I definitely need to return one day.
Mersenius is located west of Mare Humorum not far from the moon’s western limb. It is of average size but still rich in detail. The crater walls are broad and terraced; the floor has been flooded with lava and bulges markedly upwards in the middle.
My observation was done under excellent conditions with steady, transparent skies and favorable illumination. The terraces were prominent, especially on the western side (right i sketch). The convex shape of the floor was indicated by a soft shadow tracing the walls in the northern half of the crater. Two lighter rays were also clearly visible on the floor. (After checking up on the observation it seems that the northern and thinner ray, is a rille rather than a ray.) Several secondary craters were also seen, most notably Mersenius H on the southern part of the rim, and Mersenius L adjacent to the crater on the northern side.
Clavius is the third largest crater on the moon’s near side, and it can be found close to the southern limb. The crater is also one of the oldest, which is evident from the many smaller craters that mark the Clavius plain. At local sunrise the two larger of these — Clavius C and D — gives rise to a clair-obscur phenomena, giving the impression of two eyes staring back at you.
My observation of Clavius was done under a 10 days old moon, so I didn’t get to see the Eyes of Clavius (which only shows at 9 days). But the illumination nicely captured the dramatic landscape of the crater. When I started out the seeing was terrible, and I hesitated whether to continue or to call it a night. Eventually I decided to give it a shot, hoping that it might improve after a while. The turbulence settled somewhat as the moon rose, but it wasn’t enough to capture any finer detail.
Clavius C and D are the two largest craters just right of the center. The rim is marked by Porter (top right) and Rutherford (bottom right). The large adjacent crater towards the bottom left is Blacanus.
Clavius have also made an imprint on popular culture: In Arthur C. Clarke’s 2001: Space Odyssey American activities on the moon are centered around a base build underneath the surface of the crater plain. When Dr Floyd sets out to investigate the monolith excavated in Tycho, he takes the moon shuttle from the Clavius Base.
Below is a clip from 2001: A Space Odyssey showing the encounter with the monolith found in Tycho crater. The soundtrack still gives me creeps.
The largest gathering of volcanic domes on the moon can be found in the middle of Oceanus Procellarum and close to the ring-plain Marius. Squeezed into an area of approximately 200 km in diameter the Marius Hills contains about 300 domes, half of the moon’s known population. The domes are just a few hundred meters high and thus best observed under low sun.
The sketch was made under a waxing gibbous moon, just a few days from full, and the sun angle was perfect for highlighting the many domes. Sketching them was another matter, quite cumbersome at that. Marius is the crater to the middle left in the sketch. Top right is the end of the Reiner Gamma swirl.
In 2009 the Japanese Selene mission found what might be a sky light to an underground lava tunnel in the Hills. The Marius Pit is located close to the rightmost dome in the sketch, but since it is just 65 meters in diameter it is well beyond the resolution of my scope. A fly-over movie from JAXA can be found here. Lava tunnels might be an option for a future lunar base, and apparently there is advanced plans for a private moon mission to target the Marius Pit.