Have you ever seen Plato's Hook on the Moon?
It's one of many clair-obscur effects, the name given to plays of light and shadow on the lunar surface that seem to resemble familiar objects.
Plato's Hook appears within Plato crater on the Moon, when the Gamma Peak seems to cast a curved shadow.
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Finding Plato's Hook
The curious element comes from the shape of the shadow. Some reports have suggested it has a curved appearance, hence the name Plato’s Hook.
Various explanations have been put forward for this phenomenon, but capturing the hook at the right time to image it isn’t easy, due to a combination of Moon visibility, shadow timing and the weather.
Plato is an iconic sight on the Earth-facing side of the Moon.
Located at the northern edge of Mare Imbrium, this 100km crater lies within a bright highland fringe along the northern edge of the mare, its dark lava-flooded floor contrasting with its lighter surroundings.
Observing Plato's Hook
Those with larger scopes or high-resolution imaging setups will see some of the small craterlets that interrupt what is otherwise a very flat floor, but good seeing and optimal illumination are required.
The floor looks remarkably flat through smaller scopes, the perfect ‘screen’ for seeing Plato’s Hook.
Plato’s rim is well formed, a circular wall around the dark floor. The vertical profile of the rim is, as you might expect, a little irregular.
Along the eastern rim section, there’s a peak which rises to around 3km above Plato’s floor.
Known as the Gamma Peak, this casts a sharp incisor-shaped shadow across the floor when the illumination is from the east – in other words, just after lunar dawn at Plato.
If you see or photograph Plato's Hook, get in touch with us by emailing contactus@skyatnightmagazine.com
