2025 RationalWiki 'Oregon Plan' Fundraiser

There is no RationalWiki without you. We are a small non-profit with no staff—we are hundreds of volunteers who document pseudoscience and crankery around the world every day. We will never allow ads because we must remain independent. We cannot rely on big donors with corresponding big agendas. We are not the largest website around, but we believe we play an important role in defending truth and objectivity.

Fighting pseudoscience isn't free.
We are 100% user-supported! Help and donate $5, $10, $20 or whatever you can today with PayPal Logo.png!
Donations so far: $8765.50Goal: $10000

Empirical evidence for the spherical shape of Earth - The Moon

From RationalWiki
Jump to navigation Jump to search
The fault in our stars
Pseudoastronomy
Icon pseudoastronomy.svg
Adding epicycles
Epicyclists

Flat-Earthers have made several incorrect observations to claim the Earth is flat. This article refutes claims made by flat-Earthers about the Moon.

The Moon only works on a globe[edit]

Three-dimensional Moon hovering above Earth would reveal its backside[edit]

In the flat Earth model, the Moon revolves above the Earth. The Moon's declination ranges from +28.72° to -28.72°. Thus, as the Moon transits over the flat Earth, people from different places around the equator could observe different sides of the Moon at any given time. Furthermore, on the equator, people could observe the Moon's leading, bottom, and trailing sides as it passes over them, with every subsequent frame showing more from one side and less from its opposite. But we never see the back of the Moon.

Vertical pizza-Moon would be flat from its side[edit]

Dubay pizza moon.jpg

Flat-earthers deal with the issue of only one Moon's face being visible, by stating the Moon is a flat disc, like a pizza. This hasn't changed their position about where the Moon orbits. It's still hovering above Earth.

In his video Eric Dubay claims that two people standing on the opposite sides of the equator can observe the same face of the Moon at the same time, when it's facing the camera perpendicular to the observers. This is ludicrous. Even if the Moon had two identical faces, it's obvious that when a flat disc is viewed from its sides, it looks like pizza viewed from its side.

Also, even if the Moon was far enough to only see its front face, the problem would be, that a person looking at the Moon from the northern hemisphere, would see the Moon in the same orientation as someone viewing the Moon from the southern hemisphere. This is not what we see.

The Moon's orientation is upside down in southern hemisphere[edit]

Instead, people in the southern hemisphere see the Moon upside down compared to people living on the northern hemisphere.

The flat Earth model must explain this somehow.

A two-dimensional Moon in the firmament would appear elliptic when viewed from an angle[edit]

To fix the Moon as a pizza viewed from side, flat-earthers have to prevent anyone from viewing the thin side of the Moon. So they have exactly one orientation to put the pizza-Moon: horizontal, face towards the ground. This also allows explaining why the Moon is visible upside down when viewed from opposing hemispheres. In his video Eric Dubay demonstrates this with an illustration, where a picture of the Moon has been taped to the ceiling. The Moon will flip its orientation when it's viewed from opposite ends of the room.

This is however, a laughably bad explanation. In Dubay's model, the Moon will appear as a circle only when the observer is directly below the Moon looking straight up. In every other scenario, i.e. when observing the Moon from an angle, it will appear elliptical. Look no further than Dubay's own illustration above, or take Dubay's advice and tape a picture of the Moon to the ceiling and see for yourself. If you're feeling lazy you can just hover a dinner plate over your head.

The bottom line is this: Perspective forces a disc-shaped Moon to appear elliptical when viewed from an angle, which directly contradicts our everyday experience of Moon always appearing on the sky as a perfect circle.

But wait, there's more.

The Moon's orientation depends on its latitude[edit]

The Moon doesn't have only two positions. Its orientation varies, and interestingly the angle depends directly on the latitude. Since latitude lines are determined by spherical mathematics, flat-earthers can not explain it with trigonometry that operates on Moon above the Pizza land.

Diagrams showing the orientation of the Moon at different latitudes of the Earth.


Below is an example that can be reproduced with images taken from anywhere on the Globe:


Flat Earth doesn't have a model to explain why the latitude determines the Moon's orientation reliably, so they have another explanation:

"The Moon's face spins as it revolves above Earth!"[edit]

The reason why the Moon is sometimes seen upside down is according to Dubay, that the Moon spins around its axis as it transits over the night sky.[note 1] This is an absolutely ridiculous claim. Were it the case, all these time-lapses these individual words link to, should show at least a little bit of spin.

Miscellaneous arguments[edit]

"But the Moon's face should show a little bit of parallax when viewed from different sides of the globe!"[edit]

Dubay is absolutely correct here. And this is exactly what happens! (See libration)

Here is a GIF from NASA showing the Moon's face taken at the same exact moment in Tokyo and Houston on March 7, 2023:

Moon Essentials- Parallax (SVS5320 - diurnal) 2.gif

And if your "anti-NASA" filter is on then try for yourselves flatties. Grab your Nikons and photo the Moon from the beginning of the night and at the end of the same night. The images shown alternatively as an animation will show the vantage point changes in the angle from which the Moon is viewed by about 0.5°.

Diurnal libration of the Moon (animated) 2.gif

"So why is the Moon the same apparent size as the Sun?"[edit]

Anular eclipse from 2023.

They're not. That's why an annular solar eclipse is a thing. The angular diameter of the Sun varies between 0.527° and 0.545°. The angular size of the Moon varies between 0.489° and 0.568°. So they are close, but not the same. If the Earth were flat, the Sun would be the same size at the same time of day, but analemmas do not show that.

As for why the Moon is almost the same angular size, well, that's just a happy coincidence.

"But there are eclipses where both the Moon and the Sun are visible so it can't be Earth's shadow that eclipses the Moon!"[edit]

A simplified illustration that shows the basic principle, and from where a selenelion is visible.

Yes, these are called selenelions, and it happens with every eclipse. It just requires that the observer happens to stand in a spot perpendicular to the Sun-Earth-Moon syzygy, i.e. wherever it's sunrise or sunset during the eclipse. Those people can then see both objects because atmospheric refraction bends the light from behind the curve.

Dubay has claimed the refraction can't bend Earth's shadow over the Moon. This is willful misinterpretation if not straight-up deceit on Dubay's part. The light around things bends. Shadow is the absence of light, so shadow does not bend.

During the lunar eclipse, atmospheric refraction causes light to bend from the edges of the Earth, and the light that bends the least is according to Snell's law, the one with the lowest wavelength, and it happens to be red. The rainbow also bends the red light the least so it's on top. Red light doesn't bend enough around Earth to avoid the Moon, so it hits the Moon coloring it red. See this video for more information. The Moon will reflect the red light it receives, and as the reflected light travels towards Earth, some of it is again bent over the horizon. Thus the observer will see the Moon higher than it is. For an illustration, see here.

Dubay also lies some more by saying the Selenelion should be visible 180° around Earth — basically from the Sun's zenith point during the total lunar eclipse. Again, it can only be seen at the points that are 90° from the lunar eclipse.

Finally Dubay misrepresents the "8 inches per mile squared" formula — the crudest approximation available, that doesn't take into account refraction, and that works poorly on longer distances such as the radius of Earth — as an applicable formula to evaluate the Selenelion, which results purely from refraction. For the formula that takes into account refraction, see Exact Equation for the Hidden Height here.

"Oh! The spherical Moon is tidally locked? How convenient!"[edit]

Another claim from guess who is that it's a NASA conspiracy that the Moon just happens to rotate at the exact rate it revolves, and that's why we never see the opposing side. Sprinkling conspiracy dust over normal astronomical things doesn't make them conspiracies. The fact is, given enough time, every object in the sky orbiting one another will become tidally locked. The mechanism is explained here. The Moon is slowing Earth's spin in a rate that extends the day by 0.0017 seconds every 100 years. If the Sun didn't swallow the Earth in 5 billion years time, Earth would stop spinning because of the Moon, and thus be also tidally locked, in 50 billion years time.

"But a reflective Moon would show a shiny point reflection!"[edit]

Dubay has claimed the Moon can't be reflective, because then it would only reflect sunlight from a single point on the sphere (sometimes referred to as a "hotspot"). This assumes a perfect, mirror-polished planet, which it obviously isn't. There is another type of reflection called diffuse reflection, where the light is scattered at many angles due to the rough surface. The overwhelming majority of surfaces are such. The more matte the object, the more diffused the light reflecting off of it is. Light doesn't have to bounce off surfaces like a mirror so that we can see them. Everything that reflects light can be seen. That's how vision works.

"But the Moon is made of plasma!"[edit]

You might wonder where in the world flat-earthers have heard about this nonsense. From some crank weirdo named “Prof. R. Foster” who said so in a 1965 interview that the Australian ABC news channel allowed him to do for some fricking reason. Seems legit right!? Especially from a guy whose scientific credentials the ABC does not mention because they were “unable to confirm Mr Foster’s identity” or “to find any documentation of his work.”[1]

Besides the delicious hypocrisy of flatties now trying to appeal to some "scientist" as an argument from authority (whose authority is yet to be known) just because he is a "dissident" (see Galileo gambit), it is nevertheless, needless to say really, that the Moon looks nothing like plasma, at all. But hey! If flatties buy that "scientist" guy... then we are sure they'd love to know about some nigerian prince!

"But the Moon is self-luminescent!"[edit]

Dubay also co-signed Bible's claim that the Moon is self-luminescent, which is obviously not the case, as a self-luminescent surface would not show shadows exclusively on the same sides of the craters from which direction the Moon is lit up.

There is also an interesting observation that any flat-earther can do. On a sunny day when the Moon is visible, pick a ball (or a spherical object for that matter) and look at it in the same position/location the Moon is in the sky. You will see that the ball shadow will always match the current lunar phase (and even its orientation!). This makes perfect sense on a globe Earth with a spherical Moon reflecting the light of a very far away massive Sun, whose rays reach almost parallel at that scale. Thus, explaining this shadow matching very easily. But how does this work on a flat self-illuminating Moon? Is it just a coincidence? Now that's convenient![2]

"But if a rock can't reflect light nor can't the Moon!"[edit]

Yeah... Flatties have confidently (and unironically) claimed "that"... Flerfs don't know how vision works apparently. The fact that you can see rocks proves they do reflect light, otherwise rocks would be either pitch black or transparent.[citation NOT needed]

"But the Moon is transparent!"[edit]

Occultation of Jupiter by the Moon. So much so for a "transparent" Moon...

Flerfs often claim the Sun is transparent because you can't see all of it all the time. The lit up part of the Moon is always on the side of Sun. The part of Moon that doesn't get light cast upon it, stays in the shadow. What remains in the shadow receives very little or no light from the Sun, and because the Moon is blocking the stars, those lights do not come through either. Because of this, that part of the Moon is roughly as black as space. Nothing discriminates the shadow of the Moon from the nonexistent light coming from deep space, so both get colored blue because blue light waves from the Sun get scattered more than other colors in the atmosphere. Some parts of the Moon's surface will scatter some light, and so those parts appear to hover in the sky-blue.

Eric Dubay has claimed that the Moon sometimes shows stars through it. This is laughably bad. Firstly, the sky is full of stars, why is only one visible? If this is the case, why aren't flerfs posting hundreds of videos showing this every time the Moon is visible and it's not a full Moon? A much more plausible explanation is a hot pixel, or a satellite which is reflecting light from the Sun. This happens all the time. Or... maybe... you know... could a be fake edit... like ya'll flatties love to claim on every picture disproving your "beliefs".

One last nail in the "transparent Moon" coffin. In astronomy, there's a phenomenon known as ocultation, which occurs when one astronomical object is obscured by another that passes between it and the observer. Kinda like an eclipse, but involves celestial objects other than the Sun. The Moon has been recorded causing occultations many times, obscuring both planets (like Venus, Mars, Jupiter and Saturn) and stars (like Antares, Pleiades, Taurus and Zeta Arietis), even with its darker "transparent" side. With all said and done we can bury this "transparent Moon" corpse forever in the dirt.

"But the moonlight is cold!"[edit]

Dubay tried to describe moonlight as pale and cold, and based this on the idea that when its concentrated with a lens, it doesn't exhibit the slightest sign of heat.

As explained by Henk Schuring here, like Earth, the Moon receives about 340W/m², and it reflects from that roughly 8%, or, 27W/m². That energy emits in all directions, and once it reaches Earth, approximately 0.00044 W/m² is left. The Moon lights up in thermal camera videos too, so the heat coming from the Moon is not nothing, like Dubay claims.

The flerfs have claimed moonlight actually cools Earth. They did an experiment about this which showed lower temperatures under moonlight, than under a canopy. However, as explained by Dave Farina here, and demonstrated by GreaterSapien here, the experiment was a faulty party trick as it did not control for other effects by making similar temperature comparisons during the eclipse. The issue with the experiment was, it didn't account for the fact the canopy was trapping warm air, that's lighter, under itself.

To argue his case, Eric Dubay — for perhaps the first time in his life — cited an actual journal, The Lancet, that in 1856 published an article titled "Morbid Phenomena of Lunar Light". Dubay however conveniently left out the fact, that on the first page of the article, right column, line 7, it says the distance of the Moon is 240,000 miles. So clearly something is wrong with that article.[note 2] Most of the articles published in early decades of The Lancet were checked by the editor, Thomas Wakley, who was surgeon, not a physicist. Thus, perhaps it was not such a bad idea journals began standardizing peer-review of published articles in the 1950s? One would think so, especially given that Dubay blatantly lied about The Lancet having peer review at the time. For the record, Eric, The Lancet introduced peer-review in 1976.

Dubay also misrepresented the required control, by claiming the control would need to be done on the same day. The point is to measure the temperature under the shade and outside the shade, and do that during both a full Moon and eclipse. The control checks, that it's the moonlight that explains the temperature difference between shade and non-shade.

To summarize, the moonlight has no cooling effect, and it's warming effect is so small it's only detectable with purpose-built instruments. As Answers in Genesis (yeah, AiGs... the bar is very low for flatties) concludes: "the claim that moonlight cools objects exposed to it [...] defies all that we know about the nature of light and energy. Furthermore, this claim has nothing to do with flat-earth cosmology, and easily could be jettisoned by flat-earthers without jeopardizing their model."[3]

See also[edit]

Empirical evidence for the spherical shape of Earth based on the observations of

Notes[edit]

  1. Well, well. A flerf explanation that needs celestial objects to revolve around a point, while at the same time rotating around its own axis.
  2. The average distance to the Moon is 238 855 miles, so the 1856 value is so close it could've been just rounded.

References[edit]