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5 moon myths that still fool people today
earthsky.org
We frequently hear references to various moons—full moons, blue moons, Harvest Moons, supermoons, and blood moons. With so many different concepts circulating, it can be challenging to separate established facts from common misconceptions. The following discussion addresses five widespread myths about Earth's moon, presenting the scientific information that corrects these mistaken beliefs.
It is widely known that the moon consistently presents the same hemisphere toward Earth. This phenomenon has fostered the popular concept of a "dark side" of the moon, an idea frequently referenced in music and film. However, the hemisphere that faces away from our planet is not perpetually dark. It undergoes cycles of daylight and night, just like the side visible from Earth, as it is illuminated by the sun with equal frequency.
Another related misconception is that we can only observe exactly 50% of the lunar surface from Earth. In reality, over an extended period, we are able to see approximately 59% of the moon. This extended visibility is due to a slight wobble in the moon's orbital motion, known as libration. This subtle rocking motion allows observers on Earth to see a little beyond the typical edges of the lunar disk at different times, granting a view of more than just one exact hemisphere.
To human observers, the moon appears as a flawless circle in the sky, suggesting a perfect sphere where every surface point is equidistant from the center. This visual impression, however, is not entirely accurate. The moon's actual shape is an oblate spheroid. This means it resembles a sphere that has been slightly compressed at its poles. The planet Jupiter serves as a prominent example of this general shape.
An even more intriguing detail is that the side of the moon facing Earth is somewhat larger than the far side. This asymmetry gives the moon a slightly lopsided form, comparable to a gumdrop or an egg that is bigger on one end. Although the difference is small, it is measurable and real, confirming that the moon is not a geometrically perfect sphere.
A full moon set against a dark night sky often appears dazzlingly white and brilliant. Yet, in a broader comparative context, the moon is neither exceptionally bright nor truly white. It appears bright primarily due to the contrast with the dark surrounding sky. While it reflects sunlight, it is not a potent source of illumination. For perspective, imagine the brightness of a single 100-watt light bulb viewed from a distance of about 150 feet on a dark night; this approximates the brightness of the full moon.
Regarding color, the moon generates no intrinsic light of its own. It reflects all the constituent colors present in sunlight, which combine to create a white appearance. The perceived color can shift slightly with the moon's phase and its position in the sky, though these variations are typically too subtle for the human eye to detect consistently. On average, the moon's actual color is a neutral gray, similar to the shade of weathered asphalt on a road.
A prevalent belief is that the moon lacks gravity entirely. This notion likely originates from footage of Apollo astronauts moving with bouncing, seemingly floaty strides across the lunar surface. The scientific reality is that the moon possesses a significant gravitational force. Its gravity measures about one-sixth the strength of Earth's gravitational pull. This reduced gravitational intensity is what permits astronauts to achieve higher jumps and move in that characteristically buoyant manner.
The principle of gravity states that any object possessing mass also generates a gravitational field. This applies to celestial bodies like the sun, planets, and moons, as well as to smaller objects, including humans. The force may be minuscule for objects of small mass, but it is always present. Gravity is the fundamental force that maintains moons in orbit around planets and planets in orbit around stars. Without gravitational attraction, the structured universe we observe would not cohere.
It is an established scientific fact that the moon's gravitational pull is the primary driver of ocean tides on Earth. The sun's gravity also exerts a minor influence on tides, though to a much lesser extent. Some individuals extrapolate from this, proposing that if the moon can move vast oceanic bodies, it must also generate analogous "tides" within the much smaller human body. This belief reflects a misunderstanding of the specific conditions required for tidal forces to become significant.
In essence, gravitational force depends on the masses of the objects involved and the distance between them. To produce a noticeable tidal effect, the interacting bodies must be extremely large—on the scale of a planet and its moon—and relatively close together in astronomical terms. The moon is situated approximately 30 Earth-diameters away and possesses about 1/80th of Earth's mass. These specific conditions enable it to exert a pull on Earth's oceans, resulting in tides that rise and fall by several feet.
The human body, by contrast, is far too minuscule and contains too little liquid mass for the moon's gravity to induce any measurable effect. Any theoretical "tidal" movement within bodily fluids would be approximately one-thousandth the thickness of a sheet of paper. The gravitational influence from a nearby passing truck or even another person walking close by is vastly more substantial.
Furthermore, while some folklore suggests a higher rate of births during a full moon, comprehensive scientific studies have failed to identify any reliable correlation. Major medical journals have published research demonstrating no authentic link between human birth rates and the phases of the moon.
Despite the debunked myths, the moon does exert meaningful influences on humanity. It serves as a profound source of inspiration through its aesthetic beauty, such as a delicate crescent moon glowing with earthshine or during the dramatic red hue of a total lunar eclipse. There may also be more direct physical connections. Some scientific investigations have suggested a potential, though not yet conclusively proven, link between the moon's approximately monthly cycle and women's menstrual cycles.
Bottom line: There are plenty of myths that surround the moon. Here are five of the most popular. How many of these myths have you been led to believe?
In summary, Earth's moon remains a captivating celestial object, but it is often shrouded in misunderstanding. A clear comprehension of the underlying science allows for a deeper and more accurate appreciation of our closest cosmic neighbor.