Moon caves and pits are a comfy 63 degrees

Moon caves: Circular hole in gray lunar landscape, seen from orbit, with bottom visible but partially shaded.
The temperatures in the shaded area of this pit in the Mare Tranquillitatis region hold steady at around 63 degrees Fahrenheit (17 degrees Celsius). Scientists said the pit likely leads to a similarly temperate lava cave. Moon caves could be an option for future habitation for human explorers. Image via NASA/ GSFC/ Arizona State University/ UCLA.

If future explorers want to live and work on the moon, they’ll need to have a hospitable environment. The moon has virtually no atmosphere, so daytime temperatures on the moon can hit 260 degrees Fahrenheit (126° Celsius), while nighttime temps can drop to -280 F (-173 C). But a team of scientists announced on July 26, 2022, that they’ve found pits and caves on the moon that have a permanent temperature of 63 F (17 C). It’s what the scientists are calling sweater weather.

The team of scientists included Tyler Horvath and David Paige of UCLA and Paul Hayne of the University of Colorado Boulder. They published their study on July 8, 2022, in the peer-reviewed journal Geophysical Research Letters.

Moon caves, pits and lava tubes

Scientists have known about pits on the moon since 2009. NASA’s Lunar Reconnaissance Orbiter (LRO) found more than 200 pits on the moon. Horvath said:

About 16 of the more than 200 pits are probably collapsed lava tubes.

Earth is also home to lava tubes, such as those that visitors can tour at Hawaii Volcanoes National Park. They form when rivers of lava carve out pathways underneath lava flows, or when the exterior crusts solidify. The mares or “seas” on the moon are ancient lava flows that have solidified into plains. Entrances to the lava tubes appear as pits once the crust atop a lava tube collapses at a thin spot.

When analyzing the pits on the moon, the scientists found that two of the most prominent pits have visible overhangs. They said that they clearly lead to some sort of cave or void. They also believe there’s strong evidence of a large cave from a third pit’s overhang.

A cylindrical cave lit with lanterns casting a yellow glow.
Scientists believe that some lunar pits could lead to lava tubes, similar to this one in Hawaii Volcanoes National Park. The moon is home to similar tunnels, left behind after molten lava flows beneath the surface. Image via Frank Schulenberg/ Creative Commons/ UCLA.

Taking the moon’s temperature

Horvath analyzed images from the LRO‘s thermal camera – the Diviner Lunar Radiometer Experiment – to check the temperatures within the pits compared to the surface. In Mare Tranquillitatis, he studied a cylindrically shaped depression that’s about the length and width of a football field. Using computer modeling, the researchers could track the temperature changes in the pit over time.

What they found was that the temperatures remained relatively stable at about 63 F (17 C) in the shadows. And they said that any caves or tubes leading off the pit would also maintain this relatively comfortable temperature.

The key to the steady temperature, the researchers said, is the overhangs. They keep shadowy locations from getting too hot during the day and from having heat escape at night. The areas of the pit where the sun reaches bake at up to 300 F (148 C), even hotter than the moon’s surface. Horvath said:

Because the Tranquillitatis pit is the closest to the lunar equator, the illuminated floor at noon is probably the hottest place on the entire moon.

Three images of round pits on the gray lunar surface as seen from orbit.
View larger. | Scientists say that pits on the moon could lead to caves or lava tubes where temperatures would be comfortable for future human explorers to live and work. Image via NASA/ GSFC/ Arizona State University.

Moon caves are a welcome environment for humans

The extreme temperatures on the moon are a challenge for humans setting up any permanent moon base. A day on the moon lasts about 15 Earth days, and a night lasts about 15 Earth days. That would mean solar power on the moon would be inaccessible about half the time. The moon caves would remedy this issue, along with others. Moon caves would also provide some protection against cosmic rays, solar radiation and micrometeorites. Paige said:

Humans evolved living in caves, and to caves we might return when we live on the moon.

The best thermal map in the universe

The Diviner Lunar Radiometer Experiment has been mapping the moon since 2009. It has now produced the most detailed and comprehensive thermal measurements of any object in our solar system, including Earth. The researchers had to align the many images from the thermal camera until they had an accurate thermal reading down to a single pixel. Horvath explained:

Because nobody else had looked at things this small with Diviner, we found that it had a bit of double vision, causing all of our maps to a be a bit blurry.

Future exploration of moon caves

A proposed Moon Diver mission aims to send a rover in to rappel down and explore the Tranquillitatis pit. You can also read about the tiny PitRanger, designed to explore the pits on the moon.

Four-wheeled machine with big solar panel at edge of a deep, dark pit on the moon's gray surface.
Artist’s concept of a PitRanger surveying a lunar pit. Image via William Whittaker/ USRA/ Carnegie Mellon University.

Bottom line: Scientists announced that moon caves, shaded pits and lava tubes have locations where temperatures hover around a comfy 63 degrees Fahrenheit (17 degrees Celsius). These would be perfect locations for future explorers to live and work.

Source: Thermal and Illumination Environments of Lunar Pits and Caves: Models and Observations From the Diviner Lunar Radiometer Experiment



July 29, 2022

Like what you read?
Subscribe and receive daily news delivered to your inbox.

Your email address will only be used for EarthSky content. Privacy Policy
Thank you! Your submission has been received!
Oops! Something went wrong while submitting the form.

More from 

Kelly Kizer Whitt

View All