Explore the face on the Moon by observing Albategnius at the right time.
Can you see a face on the Moon?
Albategnius is associated with a clair-obscur effect known as the Face in Albategnius that occurs when the morning terminator is close, around first quarter.
The shadow of the crater’s eastern rim falls onto the internal floor to resemble the profile of a human face.
It shouldn’t need to be pointed out that this is merely an example of face pareidolia, and is one of many clair obscur effects that can be seen on the Moon at certain times during the lunar cycle.
For more advice, read our guides to the best features on the Moon and underrated features on the Moon.
Seeing a face on the Moon means your brain is recognising a face-like pattern in a random object, which some argue could be an evolutionarily advantageous trait of our ancestors to recognise potential predators obscured from view.
Albategnius is a distinctive walled plain located just east of the famous north–south crater trio of 154km Ptolemaeus, 118km Alphonsus and 98km Arzachel.
It’s closest to Ptolemaeus, the two craters separated by a piece of rough highland terrain 70km wide. The 6km crater Albategnius G sits within this highland region.
Quick facts
- Size: 136km
- Longitude/latitude: 4° E, 11.2° S
- Age: Around 3.9 billion years
- Best time to see: First quarter or six days after full Moon
- Minimum equipment: 10x binoculars
What sort of crater is Albategnius?
Albategnius is classed as a walled plain because it appears as a flat, lava-filled floor surrounded by a defined wide rim, widest in the west.
It’s pretty battered but holds its own quite well, with the exception of a section to the southwest that is interrupted by the lava-filled 45km crater Klein.
In many respects, Klein appears like a miniature version of Albategnius, its lava floor also surrounded by a relatively wide rim broken in one spot by 9km Klein A in the northeast section.
Klein is 1.5km deep and used to be identified as Albategnius A.
On renaming A to Klein, the International Astronomical Union (IAU) moved the Albategnius A designation to a rather lacklustre 7.5km craterlet in the northwest section of Albategnius’s rim.
This appears to be part of a chain of similar-sized features running north-northeast to south-southwest across the main rim.
Both Albategnius and Klein have central mountain complexes, Klein’s being small and rounded.
In contrast, the central complex inside Albategnius is impressive, rising 1.7km above the crater’s floor.
It appears as a central peak with two additional connected mountains stretching to the northeast. It’s quite reminiscent of an overhead view of an island surrounded by sea.
Observing Albategnius
If you have a large telescope or are set up for high-resolution imaging, there’s a great challenge here: the large central mountain has a perfectly placed craterlet right at its summit.
It’s tiny, measuring just 1.8km across.
As mentioned, Albategnius’s floor is flat due to it being filled with lava.
Under oblique lighting, the lumps and bumps in the floor surface may give a hint at what lies below.
Here are the ghosts of lost craters, their existence submerged beneath solidified lava.
The apparently smooth floor contains many tiny craterlets, the largest of which are around 2km across, similar to the peak craterlet mentioned above.
To the north are five craters appearing in a line: 5.7km Albategnius C, 16.2km Albategnius B, an unnamed 3.6km craterlet within B, 8.5km Albategnius N and 11km Albategnius H.
All apart from H sit on the floor of Albategnius, H being located within the northeast rim terraces.
Albategnius’s rim has some fine terracing that makes the crater look extremely detailed when the Sun is low in its sky, either near lunar dawn or lunar dusk.
This is also a good time to look out for a series of grooves running north-northwest to south-southeast near the crater and gouging its rim to the northwest and south.
Have you observed or photographed Albategnius on the Moon? Let us know by emailing contactus@skyatnightmagazine.com