Regolith
Regolith is the outer layer of rock in many planets. When the rock on the surface of a planet is exposed to air, water, sunlight, and life, it starts to wear out and crumble. It stops being one solid piece of rock, and instead becomes a collection of smaller rocks, dust, sand, ash, minerals, and organic material that came from the living things that live on it. [1][2]
On planet Earth, the uppermost layer of the regolith is what we call the soil.
On Earth, the regolith isn't the same everywhere. In some places, it's very deep. In others, it's very shallow. There are some places where there is no regolith at all, and you can see the bare rock underneath: the bedrock.
Planets and other celestial bodies that are mostly made of rock (instead of gas) have a regolith.
The Moon is almost completely covered in regolith, because a lot of meteoroids hit it and crumbled into smaller rocks. [1] The first two centimeters of the Moon's regolith is dusty, but it gets firmer underneath that.
The regolith on Mars is made of a lot of sand and dust.
Regolith Media
Surface of asteroid 433 Eros
Alluvial gravels in Alaska
This famous image of Buzz Aldrin's footprint taken during Apollo 11 shows the fine and powdery texture of the lunar surface.
Relative concentration of various elements of lunar soil
Taken from just 250 m above the surface of Eros as the NEAR Shoemaker spacecraft was landing, this image shows an area that is only 12 m across.
Martian sand and boulders photographed by NASA's Mars Exploration Rover Spirit
Regolith beneath NASA's Phoenix Mars Lander, where the descent thrusters have apparently cleared away several patches of dust to expose the underlying ice.
Pebbles on Titan's surface, photographed from a height of about 85 cm by the Huygens spacecraft
References
- ↑ 1.0 1.1 "Regolith Formation - NASA". Retrieved 2025-04-15.
- ↑ "Weathering". education.nationalgeographic.org. Retrieved 2025-04-15.