Lunar Pits Maintain Surprisingly Comfy Temperatures

Scientists found caves under the surface of the Moon that stay around 63 degrees Fahrenheit day and night

Pit on the surface of the Moon.
View from above of a pit crater in an area of the Moon called Mare Tranquillitatis, or “Sea of Tranquility”. NASA/GSFC/Arizona State University

The Moon is known for its extreme surface conditions, with temperatures dipping well below negative 200 degrees Fahrenheit at night and above 200 degrees Fahrenheit during the day. But the harsh lunar environment just started looking a bit more welcoming after a recent discovery found that the satellite's underground caves and pits keep a consistent temperature around 63 degrees.

A team of scientists studied these lunar pits across a football field-sized area of the Moon's Mare Tranquillitatis, or “Sea of Tranquility”, reports Shauneen Miranda at NPR. In their study, which was published in Geophysical Research Letters in July, they document how the pits that form above caved-in lava tubes create potentially ideal conditions for human habitation under the lunar surface.

Lunar pits—holes up to 500 feet wide in the surface of the Moon—were first discovered in 2009 by Japan’s Kaguya orbiter, and since then, more than 200 have been found, reports Rahul Rao for Space. But because of differences in how they were formed, not all pits have the same properties. Tyler Horvath, a planetary scientist at UCLA and lead author on the study, estimates that 16 out of more than 200 known lunar pits may have formed as caved-in lava tubes, according to a statement.

Similar lava tubes are found in Hawai’i and other volcanic regions on Earth, where they create long, tube-like caves. When the ceiling of one of these caves falls in, it forms a pit from above, leading down into a large underground area that, in the case of the lunar lava tubes, could potentially be used as shelter, reports Josephine Joly at Euro News.

To determine the temperatures inside the pits, the scientists analyzed images from NASA’s Lunar Reconnaissance Orbiter. Using computer modelling, they were able to determine how the temperature inside the pits changed, or rather didn’t change, throughout the lunar day and night.

Some of the pits had visible overhangs and rocky outcroppings that provide shade to their interiors, which may explain some of their temperature-buffering effects, reports Chase DiBenedetto for Mashable. Horvath also tells Bruce Dorminey at Forbes that the lunar pits could block dangerous high-energy radiation, which cannot penetrate deep under the surface.

These findings could theoretically pave the way for future human exploration and potentially even long-term habitation of the Moon. “Humans evolved living in caves, and to caves we might return when we live on the Moon,” says David Paige, a planetary scientist at UCLA and coauthor of the study, in the statement.

Briony Horgan, a planetary scientist at Purdue University who was not involved in this study, says to Rachel Fadem at CNN that this research "gives engineers who are really thinking about how to design a habitat on the Moon real numbers to work with. That'll be incredibly important going forward."