Full Moon Myths

by Brian Dunning
May 19, 2026

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Today we’re going to dig into commonly believed myths about the full moon. Not just the Moon in general, mind you, but when it’s at its full phase: when it’s on the opposite side of the Earth from the Sun, is fully illuminated, and is reflecting the full force of its moonshine glory right back at us. We’re not talking about dumb or ancient myths that nobody actually believes —  like it makes werewolves transform or it’s made of cheese or it turns sane men into madmen —  but ones that have a significant number of honest believers in today’s 21st century culture.

There are also quite a lot of factual misconceptions about the Moon, many of which were brought to light by the recent Artemis II flight that sent four astronauts all the way around it; something that hadn’t happened since 1972. Astronauts are almost always the world’s best ambassadors for science, and the crew did all kinds of Q&As with students and people all over the world for weeks upon their return —  and not only that, astronauts from all eras have always done this, including the Apollo astronauts. Among these misconceptions:

• The Moon has a dark side. No, it doesn’t; it rotates and has a day and a night like most other planetary bodies —  everywhere on the Moon gets an equal amount of daylight and nighttime. Its day is pretty long at about 29.5 Earth days, since it’s tidally locked to the Earth and rotates in sync with its orbit, presenting the same face toward the Earth all the time.
  
  
• The Moon has no smell. Yes it does! Astronauts don’t smell anything from inside a spacesuit or a space capsule, obviously, but once the Apollo guys got back inside and took their suits off they could totally smell it. The Moon’s regolith has never been exposed to water or oxygen, so it’s highly chemically reactive. Word is the Moon smells like gunpowder or wet ashes.
  
  
• The Moon is all gray. No, it’s not all gray at all, its colors range pretty much the same as rock does here on Earth. It looks white and gray from Earth because of a complicated effect in our atmosphere called Rayleigh scattering, which filters out many of the colors; and it looks white even in color photos taken by the Apollo astronauts mainly because it was so brightly illuminated by the Sun, contrasted against the black sky. Newer photos —  as in the one used for the cover image for this episode —  show it in its real colors. Much of it is gray, but a lot of it varies among the colors of beach sand here on Earth. Mineral-rich regions are orange, tan, ranging to almost purple as you see in our own deserts.

And then, of course, there are the conspiracy theories, all of which have this unbelievable staying power. Populist-driven distrust of expertise continues to maintain a strong grip worldwide, so just about any subject that has experts is dismissed by those whose innate common sense knows better. Two of note that we’ve covered here on Skeptoid:

• NASA faked the Moon landings. This one continues to thrive, astonishingly. It’s such a deep subject I had to make this one a three parter, episodes #535 through #537. Part 1 talked about the history of the claim and how it grew out of Christian fundamentalism; part 2 debunked a lot of the individual details of the claim; and part 3 went through the physical, unambiguous, undisputed proofs that humans from Earth traveled to the Moon, landed, and returned safely.
  
  
• The Moon is an engineered structure. Weirdly, there’s a subculture who believe the Moon is not a natural satellite but was constructed in place by some advanced race long ago. It seems like a super weird thing to think, but where it gets really cool is in the ways that we’re able to prove it’s not true.

But today we get to do ourselves a favor and move away from the fringier stuff and onto ideas that are more mainstream, that don’t require some preexisting pathology to believe, the things that might come up in the course of normal, intelligent conversation.

Let’s get started with a couple that nearly everyone has heard:

Crime is higher during a full Moon

A full moon rises, and people go kind of nuts — so the urban legend claims. However it turns out that the data does not support this, even though it also shows that people do believe it.

A 2017 study in Brisbane, Australia examined eight years of over 900,000 phone calls to the police to determine whether there was indeed a higher number of calls during a full moon, and found no statistically significant correlation. As far as what the police themselves believe? Research on this is harder to come by, but a 1986 survey of Miami Beach police officers and people on the street found that police officers were indeed statistically more likely than civilians to believe that crime goes up during a full moon — even though it demonstrably does not.

Emergency rooms are busier during a full moon

This is another one that everyone seems to believe, and it actually makes a little bit more sense since this includes psychiatric emergencies. Someone who believes themselves to be a little bit nuts might plausibly see a full moon and work themselves up into a frenzy for no other reason. Two interesting things here: First, if that does happen, it’s not statistically significant enough to show up; and second, psychiatrists tend to believe the emergency room myth even more than other ER staff.

On a related note, a small number of studies — one from Indiana and one from Finland — have found that suicides do indeed go up during a full moon; in one, the effect was more pronounced among older people, and in the other, the effect was confined to premenopausal women and only in the winter. However, both studies have failed attempts to replicate their results. The hypothesized mechanism was not anything mystical about the full moon, but rather light exposure and sleep disruption.

The most often cited paper on hospital visits during a full moon is from 2011 from the World Journal of Surgery and examined nine years of records from the hospital data system in Germany. There was no increase during full moons. The study also looked at surgical complications, Friday the 13th, zodiac signs, and other characteristics, but — big surprise — none of those made any difference either. It’s noteworthy that some studies do show a small link, but most don’t.

Emergency rooms are also the source for dog bite data, and surveys do show that staff believe there are more dog bite admissions during a full moon. But as in the other cases, the data does not support this.

A full moon is the most effective time to conceive a pregnancy

There are all kinds of beliefs about giving birth and the full moon, nearly all centering on the Moon being correlated with high birth rates, high conception rates, and reduced complications. This likely goes all the way back to Roman mythology in which Luna is the fertile mother goddess. Yet it is pretty thoroughly debunked. Numerous studies over the decades, including a 2005 one from the American Journal of Obstetrics and Gynecology that looked at over half a million births in North Carolina, found no correlation at all between the moon phase and any of these metrics.

A related concept, mainly found in New Age wellness culture, is called “lunaception,” where some people think that ovulation can be manipulated by sleeping with blackout curtains every night except for three nights during each full moon; the idea being that some sort of Mother Earth energy is strongest when conception is aligned with the full moon. However, large scale studies have found that the practice affects neither ovulation cycles nor pregnancy inception rates.

There’s also a belief in India — supported by a few, low-quality studies —  that conceiving during a full moon is more likely to produce a boy. But the belief is thoroughly disproven by a large number of much larger studies from the rest of the world.

A full moon is the best time to catch fish

I’m probably going to get tarred and feathered for this, because the belief appears to be extremely solid among many fishermen, and even some fishing magazines publish articles to this day reinforcing the belief. But as far as freshwater fish go, the answer is a resounding no. It’s been studied extensively (I mean, anyone who fishes would be highly motivated to study this). One of the most often cited was conducted at Carleton University in 2008, when researchers tracked the movements of tagged fish in a lake for an entire year. It concluded that “no repeatable patterns were noted in relation to lunar periodicity.”

This might not always hold true for saltwater sportfishing, however. A review of 190 studies was published in Reviews in Fish Biology and Fisheries in 2024, and it presented a complex picture. A lot about game fish behavior changes at night and under different nighttime lighting conditions, as things like baitfish schools and zooplankton generally stay in deeper water during full moons. But the game fish are still hungry, and most studies have found that the moon phase makes no difference to how many of them are caught. One rare exception might be swordfish, which may bite more often during a full moon according to a small amount of data; other billfish and saltwater fish don’t appear to have any such correlation.

Earthquakes are more likely during a full moon

This is one that seems plausible, as the Moon’s gravity does actually knead and warp the shape of the Earth, potentially freeing stressed faults. And indeed, there is a correlation between earthquakes and tides. This is seen along deep-sea faults, and usually during the lowest tides; as the combination of reduced gravity and reduced pressure from the weight of the ocean is what it takes.

As the full moon goes, tidal forces can result in the annual highest high tide having up to a 20% greater range than the annual lowest low. But while that sounds like a lot, it comes from a difference of only 0.0000245% in the gravitational force, which is completely insignificant compared to that of the daily tides. The full moon’s influence on earthquakes is a homeopathic drop in the ocean.

The Moon does play a role in legitimate modern psychology

Some people have heard this, and it is indeed a claim made in “psychological astrology.” This is a pseudoscientific blend of various psychology offshoots and astrology. It mentions Carl Jung a lot, and this makes it sound like it must be a real thing to some non-experts, but it’s not. Nowhere in any modern psychology courseware or textbooks is the full moon mentioned, or even hypothesized to play any role at all.

So that’s a quick survey of the sanest-sounding, least Medieval myths about the full moon that I could turn up. There were a couple of these that I didn’t know myself, as so many of them have a plausible-sounding element to them. So you are now armed and prepared should you encounter a friend or coworker —  at least, you are if their issue is believing in one of these handful of relatively tame misconceptions. If they think the Moon is made of cheese, well, you might just have to give in and acknowledge it.

By Brian Dunning
Follow @BrianDunning