Waxing half Moon at 46 % · the crater hour of the evening sky
The waxing half Moon is the Moon of the early hours. It already stands high in the sky at sunset and belongs to the first half of the night — the counterpart to this gallery's waning three-quarter Moon, which has to be earned at two in the morning. And it is the crater hour par excellence: the terminator runs right across the disk, exactly where the great walled plains and mountain chains lie.
The date was not recorded — the registration found it again. No time of exposure has come down to us for this image. Geometric registration against NASA references for various days settled the question unambiguously: the evening of October 21, 2012 fits with 131 image matches and a residual of 2.9 pixels, while the neighboring days either fail or fit measurably worse — and only on the 21st does the terminator lie exactly as the image shows it, with the Alps half lit, Plato and the Apennines still in the night. That places the panorama in the same October series as the two other lunar images: October 21 (waxing, 46 %), October 7 (waning, 63 %) and October 29 (full).
What the terminator lays bare here is the complete first-quarter programme: the Apennines emerging from the night, the fully lit Mare Serenitatis in the lunar morning, the crater triplet Theophilus, Cyrillus and Catharina, the Altai Scarp as a curved basin rim, and in the south the battered highlands. North is at the top in this image; the crops work their way from pole to pole.
Together the three lunar entries are a lesson in a single point that the Moon article develops: the illumination decides what a lunar photograph shows. The same regions appear here in the grazing light of the lunar morning, in the three-quarter Moon from the opposite direction — and at full Moon as a pure brightness map without any relief at all.
All labels are computed, not placed by eye: the image was geometrically registered against the NASA reference for the determined hour, and the names follow the official USGS/IAU nomenclature. Details are given under "Capture and processing".
Crops
North polar region
The north polar region — the same ramparts, the other light
W. Bond, Goldschmidt and Meton again — the same foreshortened polar region that the three-quarter Moon entry also shows, only this time the light comes from the other side: there it was lunar evening, here it is lunar morning.
Compare the two crops and you see the same rampart lit once from the east and once from the west — the simplest illustration of the fact that lunar observers get the same region “anew” several times over the course of a month.
Alps at the terminator
The Alps and the Alpine Valley in first light — Plato is still waiting
Sunrise is just reaching the Montes Alpes: the peaks are already catching light while Plato behind them still lies entirely in the night — no more than a marked circle to be guessed at in the dark. Running dead straight across the range is the Vallis Alpes.
Aristoteles at the right already stands in full morning light and shows its terraces. A day later Plato would be out; two days later the relief here would already be half gone again — at the terminator every hour has its own picture.
Mare Serenitatis
The Sea of Serenity in the lunar morning
Mare Serenitatis, fully lit and yet still in low morning light: the basalt plain shows its wrinkle ridges and the fine brightness steps of the individual lava flows. It is framed by the Montes Caucasus and the Montes Haemus — remnants of the basin rim.
At the edge lie the dark Lacus Mortis and the terraced Hercules. The Serenitatis basin is one of the giant structures of the Great Bombardment — the timeline for it is in the Moon article.
Rille country
Grabens and lava patches at the center of the disk
Near the middle of the lunar disk lies terrain that looks unspectacular but is finely drawn: dark lava patches between half-sunken craters, threaded by dead-straight rilles. Such Rimae are extensional grabens and collapsed lava channels — tectonics in miniature, made visible only by grazing light.
The cataloged neighbors Rima Hyginus and Rima Ariadaeus are marked just above; their offshoots and relatives run through this crop.
Theophilus trio
Theophilus, Cyrillus, Catharina — three ages in a row
The Moon's most famous crater triplet, caught perfectly at the terminator: Theophilus with a sharp rampart and central peak, beside it Cyrillus, whose rim is overprinted by Theophilus, and the still older, softened Catharina.
The overlap is the point: whichever cuts through the other's rampart is the younger — the same shadow stratigraphy as on the three-quarter Moon, here in a single row of three. To the right the Mare Nectaris begins.
Stöfler & Maurolycus
Stöfler and Maurolycus — the reunion under reversed light
Stöfler and Maurolycus, the two veterans of the southern highlands — they too a reunion with the three-quarter Moon entry, under reversed illumination. This time the Sun stands in the east, and the younger impacts on Stöfler's floor throw their shadows to the other side.
That two images of the same region look so different is not a weakness of photography but its tool: only two directions of light together show the full form.
Chain at the terminator
Purbach, Regiomontanus, Walther — the chain emerges
Between the Rupes Recta scarp (marked above) and Stöfler, a chain of large old walled plains pushes out of the night — the region around Purbach, Regiomontanus and Walther. Their eastern ramparts are already glowing, their floors still lie in black.
It is exactly at this edge that the famous “Lunar X” forms at the half-Moon phase — a cross of light made of touching ramparts that shines for only a few hours. One more reason why the first quarter is the lunar observer's favorite phase.
Southern terminator
The southern highlands in the first hour
In the far south, where the craters crowd together anyway, the low Sun breaks the highlands into a pattern of glowing ramparts and black floors. Hardly any surface is level: here lies the oldest, most densely struck crust of the near side.
The large Moretus with its central peak stands just outside the crop — marked at the edge. The region rewards comparison with the three-quarter Moon entry, where the same area stands in evening light.
Apennines in the morning
The Apennines emerge from the night
The most dramatic moment of the crop set: the Montes Apenninus — the upthrown rim of the Imbrium impact — stand as a glowing front right at the terminator, with Mons Huygens and Mons Bradley as the first islands of light. Archimedes behind them is only half out of the night.
At Palus Putredinis the Rima Hadley is marked — the Apollo 15 site, which the three-quarter Moon entry shows in full relief. Mare Imbrium itself still lies almost entirely in darkness: its sunrise comes only a day later.
Tranquillitatis & Lamont
The Sea of Tranquillity — and a crater that barely exists any more
Mare Tranquillitatis, the sea of the first Moon landing, in low morning light. This is exactly the illumination one needs for Lamont: a sunken crater of which only a pattern of wrinkle ridges in the basalt remains — under a high Sun it vanishes completely.
A ghost crater like this one is archaeology in grazing light: the lava buried the structure, but its settling traces the old ring as a shallow relief — centimeters per kilometer, visible only when the light falls almost horizontally.
Rupes Altai
The Altai Scarp — the rim of a basin
The Rupes Altai runs across the image as a bright, sweeping wall — not a fault in the terrestrial sense but the outer ring of the Nectaris basin left standing: the petrified shock wave of a giant impact, some 500 kilometers long.
At its southern end sits the sharp Piccolomini, farther north Sacrobosco and Catharina — and whoever follows the line onward arrives back at the Theophilus trio on the basin rim. In the grazing light of the first quarter the scarp is as distinct as it ever gets.
Acquisition and processing
The exposure belongs to the October 2012 series and was made with the same chain as the two other lunar panoramas in this gallery: a GSO 8″ f/4 Newtonian with 800 mm focal length, a Tele Vue 2.5× Barlow and an ALCCD full-HD planetary camera. The Moon was filmed in video sequences, reduced by lucky imaging to the sharpest moments, and assembled tile by tile into a panorama of 3,786 × 5,052 pixels. The AVIF version was output in 2026 from Photoshop/Camera Raw with an HDR gain map.
The date is reconstructed, not handed down: registration against phase- and libration-correct NASA references for various hours identifies the evening of October 21, 2012 unambiguously (reference 18:30 UT, illumination 45.7 %) — 131 geometrically consistent image matches at a median residual of 2.91 pixels, while the references for the neighboring days either fail or fit markedly worse. The official coordinates from the USGS/IAU Gazetteer of Planetary Nomenclature were then projected into the image. The procedure serves reliable naming — it is not a photogrammetric height measurement.