Crater of eternal darkness


A crater of eternal darkness is a depression on a body in the Solar System within which lies a point that is always in darkness.
A related term is permanently shadowed regions. As of 2019, there are 324 known permanently shadowed regions on the Moon.

Location

Such a crater must be located at high latitude and be on a body with very small axial tilt.
On the Moon, permanent shadow can exist at latitudes as low as 58°; approximately 50 permanently shadowed regions exist in the 58°- 65° latitude range for both lunar hemispheres.

Conditions inside craters

Craters of eternal darkness might be advantageous for space exploration and colonization, as they could potentially preserve sources of water ice. Several of such craters show indications of water ice in their interiors, including Rozhdestvenskiy and Cabeus craters.
In some cases, peaks of eternal light are located nearby, that could be advantageous for solar power generation. For example, there are 2 peaks near Shackleton Crater that are illuminated a combined ~94% of a lunar year.
Permanently shadowed regions have a stable surface temperature. On the Moon, the temperature hovers somewhere at or below 50 degrees Kelvin. Another temperatures estimate is 25 K to 70 K. On the other hand, computer simulations show that powerful solar storms can charge up the soil in permanently shadowed regions near the lunar poles, and may possibly produce "sparks" that could vaporize and melt the soil.

List

Below is an incomplete list of such craters:
The Moon:
Mercury:
Many such craters also exist on Ceres.

Research missions

In 2009, LCROSS sent an impactor into a Cabeus crater, that resulted in detection of water in the ejected material.
In 2018, an analysis of the results of the Moon Mineralogy Mapper confirmed the existence of water ice deposits in permanently shadowed craters and crevices, with more abundance near the south pole.
Lunar Flashlight is planned to launch in 2021 as a secondary payload for the Artemis 1 mission.
A camera called ShadowCam is being built that will be able to take high-resolution images of Permanently Shadowed Regions. It is a NASA instrument that will fly on board the Korea Pathfinder Lunar Orbiter in 2022.