Flammarion is an inconspicuous walled plain near the centre of the Moon’s disc.
In this guide we'll reveal how to locate it on the Moon, and what you can see in the surrounding regions.
Key facts
- Type: Walled plain
- Size: 75km
- Longitude/latitude: 3.7° W, 3.3° S
- Age: Older than 3.9 billion years
- Best time to see: First quarter; six days after full Moon
- Minimum equipment: 50mm telescope
Locating Flammarion
On the Earth-facing side of the lunar surface, there are two great crater ‘chains’ containing three large craters.
On the western side of 350km Mare Nectaris is the roughly north–south chain formed by 101km Theophilus, 98km Cyrillus and 100km Catharina.
Further west, lying roughly on the Moon’s central meridian at the same general latitude as the Theophilus chain, and running from south to north, are 98km Arzachel, 118km Alphonsus and 154km Ptolemaeus.
Immediately north of Ptolemaeus is 41km Herschel. To the north and slightly west of Herschel, lies 75km-diameter Flammarion, appearing like a mini Ptolemaeus.
Observing
Flammarion's floor is lava-covered and, like Ptolemaeus, remarkably flat, with little evidence of any features visible through smaller amateur telescopes.
Larger kit may show some of the 1.5–2km craterlets on the eastern part of the floor, especially the trio of small co-joined craterlets towards the north which, combined, should be a little easier to see, especially under oblique lighting.
Its rim is very old and quite battered. The southern section appears to be formed from several massifs which are separated at floor level by small gaps.
To the southeast is a larger ridge that rises to around 1,600 metres.
To the north, the rim is open, co-joining Flammarion to 31km Mösting M, a severely battered feature hardly recognisable as a crater.
About half of Mösting M’s rim is missing and the crater’s floor is flat with a rough texture.
The northern part of Flammarion’s floor contains 4.3km Flammarion C, nestled within a small northern extension to the main crater rim.
Running east–west across the floor immediately south of Flammarion C is Rima Flammarion, a trench 70km or so long and 2km across at its widest section to the west, narrowing to 1.2km south of Flammarion C.
Outside of the northeast rim, the rille appears to continue east, becoming a feature known as Rima Oppolzer. This runs east from 6km Flammarion W for around 170km.
Returning to Flammarion, the distinctive 12km crater embedded in its western rim is 12km Mösting A, Mösting being the youthful, sharp 27km crater further to the north.
Similarly, the 10km crater immediately south of Flammarion is a satellite of Herschel, known as Herschel C.
The smaller 6km craterlet that sits between them, roughly two-thirds of the way from Herschel C towards Mösting A, is Flammarion B.
It’s interesting to contemplate what the Moon’s surface would look like from inside a walled plain such as Flammarion.
Standing at its centre, your horizon would appear flat, with only the edge of the floor visible as your horizon – apart from to the southeast, where you’d see the rounded peaks of the highest section of Flammarion’s western rim poking up.
If you have images of this lunar feature, we'd love to see them! Email them to us via contactus@skyatnightmagazine.com
