Yes, the moon is shrinking

Did you see all these articles about the moon shrinking? Do you need to be worried?? Let me break this down for you.

Over the past few hundred million years, the moon has shrunk over 150 feet. We’ve known this for awhile now. But it’s in the news again because scientists have uncovered that it’s been causing landslides and other seismic instability near the lunar south pole. For context, that’s where NASA is planning on landing astronauts in the next few years with the Artemis program. Here’s what’s going on, and whether it’s actually a problem.

Let’s start with WHY the moon as shrinking. Well, as its interior cools, the moon loses heat, which causes it to shrink. Think of a fruit like a grape going bad, and how it shrinks slightly and develops wrinkles. That’s pretty much what’s happening to the moon.

It’s getting wrinkly, but unlike a grape, the moon’s outer crust isn’t exactly flexible. That means that this shrinkage can cause seismic activity — we’re talking moonquakes, fault lines, and other issues.

A new paper from The Planetary Science Journal focuses on the south pole of the moon — which is an area NASA has proposed for the Artemis III crewed landing, currently scheduled for NET than September 2026 (for more on the delays to NASA’s moon missions, check out my video on the Artemis program).

During the Apollo program, astronauts placed seismometers on the lunar surface to measure seismic activity like moonquakes during Apollos 11, 12, 14, 15, and 16.

Now, scientists have linked fault lines in the lunar south pole region, identified in photos that the Lunar Reconnaissance Orbiter took in 2010, to the most powerful moonquake these seismometers have ever recorded, which occurred on March 13, 1973.

This can lead to warping of the moon’s surface in the polar regions. It’s also important to note that many of the quakes caused by these fault lines occurred when the moon’s orbit took it furthest from the Earth. That’s when the tidal stress on the moon’s crust from the Earth is at its peak.

What does this mean for a potential moon mission? Well, any sort of outpost or exploration mission could be greatly affected by these moonquakes. They’re relatively shallow, so they could cause damage to buildings, but also unlike earthquakes, they can they can last for hours.

And because the moon’s surface is dry — gravel and dust — that makes it more prone to landslides than Earth. That could be a problem if one occurs while a team of astronauts is on the lunar surface.

It’s always good to have more information on these kind of issues, especially as NASA plans for the Artemis missions. But trust me, beyond that, you do not need to be worried about the moon shrinking.