The Moon, our celestial neighbor, holds many mysteries that have yet to be solved. Among its mysterious features are areas that have never been illuminated by the Sun. These eternal shadows, hidden in some craters located mostly in the polar regions, are of interest to space agencies around the world. Recent spacecraft missions have revealed the presence of water ice in these areas, making them prime targets for future exploration by Mars rovers, landers and eventually humans.
Inclined Moon: A Unique Phenomenon
The reason why sunlight never reaches these shadowed areas is due to the Moon’s peculiar tilt. Unlike the Earth, which has an inclination of 23.5 degrees relative to the plane of its orbit, the Moon is almost vertical and has a tilt of only 1.5 degrees. This means that regardless of its position in orbit around the Earth, the sun’s rays fall almost perpendicularly on the Moon. Thus, while the equatorial regions are flooded with abundant light, the polar regions are plunged into perpetual darkness, reminiscent of late afternoon in winter on Earth.
Craters: Gatekeepers of eternal shadows
If a single mountain on the Moon doesn’t create permanent darkness, a rimmed crater is a different matter. In such craters, the bottom and part of the wall remain in perpetual shadow because of the location of the rim. As the Moon rotates, the shadow changes, resulting in areas that never get direct sunlight. The sun is forever hidden behind the rim, plunging these areas into perpetual twilight.
Cold Traps: Places Where Water Hides
These shaded areas, aptly named “cold traps,” provide a unique environment for water storage. Persistently low temperatures, reaching below -160°C (-260°F), prevent the ice formed there from evaporating or sublimating. Instead, the ice behaves like rock, remaining frozen for billions of years. Most of these cold traps, about 60%, are located beyond 80 degrees latitude at the Moon’s South Pole, making this region of particular interest to space agencies.
Race to the Lunar Poles: A Multinational Effort
Many countries have set their sights on exploring the Moon’s polar regions. Russia’s Luna-25 spacecraft plans to reach these regions within days, followed by India’s Chandrayaan-3. China also plans to send the Chang’e-7 lander and Mars rover to the Moon’s south pole in 2026, while Jeff Bezos’ company Blue Origin is preparing a private mission. In addition, NASA’s Artemis 3 mission to return a man to the moon is planned for December 2025. However, due to mishaps caused by SpaceX’s Starship explosion and subsequent damage to the launch pad, Artemis 3 may undergo modifications and rule out landing in the polar regions of the Moon.
Uncovering the origin of lunar water
The presence of water on the Moon is due to a variety of sources beyond ice found in cold traps. Hydrated minerals and glass beads formed from collisions between the Moon and smaller celestial bodies in the solar system also contribute to the water content. Water molecules themselves are found throughout the Moon’s surface, including in sunlit regions where these precious molecules are contained in dust grains.
Unlocking the secrets of the Moon
As scientists and space agencies continue to search for the Moon’s mysteries, exploration of its polar regions promises to yield invaluable results. As water ice is a potential resource for future human settlement and scientific exploration, these shaded craters hold the key to humanity’s future endeavors beyond Earth.