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Episode 167 - Modern Eclipse Lunacy, Part 2: Flat Earth

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Recap: The August 2017 total solar eclipse was seen by hundreds of millions of people, and yet some of them have tried to use it to promulgate pseudoscience. In this Part 2 episode, I discuss ideas about the eclipse promoted by proponents of the idea that Earth is flat.

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Episode Summary

Overview: In this second part of the Modern Eclipse Lunacy series, which *should* total three regular episodes, I'm going to focus on the claims of those who think Earth is flat, and what they had to say about the total solar eclipse we had back in August 2017.


But, before I get to that, I'm going to go old-school podcast and get into the background first because it's due to the mainstream model of how solar eclipses - and lunar ones, for that matter - happen that flat Earth proponents ("flatEarthers" for short) that they have issue.

The study of Earth's shape goes at least as far back as the ancient Greeks who were able to calculate its circumference to an accuracy of about 2% off from the modern value. It certainly goes back further in time because of efforts of navigate via waterways, you kinda have to have a concept of a spherical planet to get latitude correct when you're out at sea and using the stars. But, at the very least, this shows that at least 2200 years ago, at least one group of people on the planet knew that Earth was round and not flat.

Tuck that aside for a few minutes, and we can discuss why eclipses occur, assuming spherical planets and moons. An eclipse, to boil it down to the original meaning, is derived from Latin "ekleipein" which meant "to fail to appear." The modern meaning in astronomy is when one body in the sky, from our vantage point, covers another body in the sky. We tend to put an adjective in front for the body that is being covered, such that a lunar eclipse is when the moon is covered, and a solar eclipse is when the sun is covered.

A lunar eclipse happens when Earth passes directly enough between the moon and sun such that Earth's shadow, when cast by the sun, falls on the moon. A solar eclipse happens when the moon passes directly enough between Earth and the sun such that the moon's shadow, when cast by the sun, falls on Earth. Since Earth is much bigger than the moon, Earth's shadow in space is bigger and the moon also has less surface area to be covered, which is why lunar eclipses are a bit more common than solar and why they last much longer.

With those basics in place, there's also the factoid about orbital path. Moon's path around Earth is tilted by about 5° relative to Earth's path around the sun. That means that it spends the vast majority of its time either above or below the sun, as seen in our sky. Just as if you were to put two rings together, one slightly smaller so it fits in the other, and tilt them, you get two points where the rings touch, the same is true for Moon's orbit around Earth: There are two points in the orbit where it crosses that path of Earth around the Sun, and it's only at or very, VERY near those points that you can get an eclipse. And, while there's a bit of wobble in how those line up, they tend to line up as you might expect: Two points in the moon's orbit line up with two points in Earth's orbit, such that we get eclipses roughly every 6 months.

Since I've talked a lot about that background information before, that's all I'm going to discuss in this episode. Returning to the shape of the planet, it's said that Galileo was one of the first to use eclipses to demonstrate Earth is spherical: The shadow cast by Earth on the moon, during a lunar eclipse, regardless of which part of the world is seeing the lunar eclipse, is always a circle. If Earth were flat, or a short squat cylinder as I talked about in Episode 33, that shadow might be a circle at one point, but if another part of Earth is facing the moon when you get the lunar eclipse, then it should be a compressed circle, and eventually you should see a lunar eclipse where the line of the flat Earth is being cast on the Moon. Because you don't, that shows Earth isn't flat.

With that in mind, let's look at what some flatEarthers were saying in August.


I'm going to go from the crazy end to the slightly saner end in this episode. I already had a headache when starting to research it because I haven't been drinking enough water, but reading the rantings of a rapper named B.o.B. did not help that headache. As a sentence of background, B.o.B. is a rapper who, in 2016, announced to his 2.3million Twitter followers that Earth is flat, which prompted a response from even Neil deGrasse Tyson.

I'm going to go through a few of the tweets and some responses by his followers that Hemant Mehta posted over at The Friendly Atheist blog.

He started out by tweeting, "it's so amazingly beautiful how the moon can pass in front of the sun multiple times in one day"

Yeah, that's how he started. I looked through the thread of replies to try to understand what makes him think that, but I was unsuccessful. Perhaps the best responses in my opinion were the ones telling him to read a book, and that he shouldn't think second grade questions are the epitome of intellectual probing and discourse. But just in case you're wondering, no, the moon doesn't pass in front of the sun multiple times in one day, it takes one lunar month which is just shy of a calendar month (except non-leap-year Februaries) to go through our sky once.

The next tweet was, "It's so amazingly beautiful how the moon isn't visible before and after a total solar eclipse"

Unfortunately, this is something I've heard from more than just flatEarthers, so I want to explain it here. The moon, by itself doesn't emit any light -- though I'll get to that later because B.o.B. weighs in on that, too. It reflects light. We see it lit by the sun, but we can also see it lit by Earth. In the first situation, sunlight bounces off the moon and some of it comes to Earth and we see that illuminated portion. In the latter situation, sunlight bounces off Earth - which is larger than the Moon and over 4 times more reflective - so off Earth, onto the moon, and back to Earth. If you have a thin crescent moon in the twilight sky, you can often even with your unaided eye see the sunlit portion and then the Earthlit portion, too.

But, during the day, that Earthlit portion is too dim relative to the brightness of the sky, and you can't see it unless you do some very careful photography and computer processing of those images.

Under the standard model, the moon is very close to the sun just before and just after a solar eclipse, so that Earthlit portion is not going to be visible relative to not only the brightness of the sky, but the glare of the sun.

One of my favorite responses to his tweet was, "Statements like this are why we should never cut funding to education"

The next tweet gets to what the flatEarthers - or SOME flatEarthers - think actually causes the eclipse, in one word: "Rahu." Rahu is the severed head of, effectively, a Hindu demigod, that swallows the sun and causes eclipses in that mythology. In Vedic astrology, it's one of the nine planets. So, flatEarthers - or again, SOME flatEarthers - have adopted the idea that Rahu actually exists and it is what causes solar eclipses. As a demigod, then it doesn't need to follow any normal laws of physics, I suppose, but if you like your universe to try to be consistent, you could see any of my more than dozen episodes on Planet X, perhaps most relevant being Episode 109 on Marshall Masters' ideas. My favorite response to B.o.B.'s tweet was an image of a jar of Ragu pasta sauce.

After an hour or so, B.o.B. started to respond to some of his critics. One of them wrote, "You realize that the only reason you see the moon in the first place is because the sun casts light on it right? All light is behind it now." B.o.B.'s response was, "according to a textbook yes, but the moon actually generates its own light."

I told you before that he has ideas on moonlight. This idea is surprisingly common among flatEarthers, saying that the moon emits its own light and doesn't get any from the sun. I think they have to say that at least under some flat Earth models because in those models, the sun and moon are basically flashlights aimed down on the planet, and that's why only some parts are in daylight or moonlight at any given time.

FlatEarthers will also claim that moonlight is colder than ambient light, such that if you take a thermometer and measure something in moonshadow, it will register a warmer temperature than that object in moonlight. To say this is wrong is an understatement, but I can think of one legitimate scenario where that measurement could have been made and led to this erroneous conclusion: Basically, different stuff cools at different rates. As a very simple example, if you've ever been on a beach at sunset or sunrise, you should've noticed that the sand very rapidly changes temperature in response to the presence or absence of sunlight. In contrast, a large rock will retain its heat or lack-there-of much longer than the lose sand.

As another example, water is able to retain its heat a very long time, which is why it takes so long for it to heat up as opposed to something else. It's also why it's a good - if heavy - insulator. I actually had an officemate in graduate school who was modeling this for rocks embedded in the surface of Mars to try to predict if the Mars Phoenix lander would find ice near the surface. All her code did was model the exchange of heat and track temperature given different parameters for how well different material retains heat. She also did lab work to make some of those measurements of heat retention herself.

So I could imagine a situation where someone measured the temperature of one material that was in the shade of something from the moon and got one temperature, and then went out of that shadow and measured the temperature of a different material, and gotten a different reading. I don't know if that's how this false idea came about, but it's the most plausible scenario I can come up with, giving them the benefit of the doubt they didn't just make it up.

Getting back to the tweet, my favorite response is again, "This guy. Right here. This is why we need MORE emphasis and effective investment in our education system." They then made a political statement about the current Secretary of Education in the US, but this isn't that kind of show so I'll refrain.

My favorite snarky response tweet was, "How can it be made of cheese and still generate light??? Please explain"

In response to a tweeter who wrote, "So you're telling me there are light bulbs in the moon? How the hell does it generate light? It's a rock. Is it flat to you too?" B.o.B. wrote, "a spherical object doesn't reflect/refract light evenly across its surface."

I wasn't able to decipher what he meant by that until someone posted a picture showing, effectively, a disco ball. The disco ball when illuminated by one light shows a bright reflection along a direct line of sight to the light source, and varying illumination that fades away as you go more indirect from that light source on the body. Apparently what he was trying to say is that the full moon should show that kind of illumination pattern, with what we call a bright specular reflection, rather than what appears to be an evenly illuminated disk.

I guess that was supposed to answer the question asked by making the point that if the moon is a sphere illuminated by the sun, we should see that kind of light pattern rather than what appears to be an evenly illuminated disk, therefore it must generate its own light.

What this ignores is many things, such as, different materials reflect light differently (just look at a dishrag versus a spoon); but instead of talking about those, I'm going to point out the inconsistency: What B.o.B. is saying is that the moon MUST have its own light source because, if it didn't, and it's a sphere, then it MUST look different from how it does. Right there in that argument, he's giving away that the moon is a sphere. Because, if the moon were flat AND illuminated by the sun, then it SHOULD have the even illumination we see during a full moon! By saying it must emit its own light to solve this problem, he is giving away that the moon is a sphere.

Moving on, in two tweets a mere two minutes apart, he wrote "that same blue dot appeared on everyone's pics... it's not the moon" and then tweeted a picture showing that dot and wrote, "this was taken by me during the eclipse ... how is the moon blocking the sun if it's way down there"

So again, he's being insanely inconsistent. Either that blue dot is the moon or it's not. If it isn't, then you can't use that as an argument against the standard model.

What it actually is should be obvious to most skeptics who have dealt with various paranormal claims that use photographs as evidence: It's a simple lens flare.

Someone stated, several hours later, "I like B.o.B.'s thought processes and his 'car talk.' I believe he knows more than I do but, if the Earth wasn't round then explain gravity" B.o.B. responded with one word: "Density"

This set off a long tweet thread but I liked the response of, "Explain density without gravity." Someone else tried to say, "Density=GravityGravity=Density A table is more dense than the air so the air cant support it, thus it falls. Helium gas is less dense. Done."

As pointed out by the original questioner, "You didn't explain density without gravity. If density is your explanation for gravity, you can't use gravity to define density"

In response to that, the tweeter wrote, "I made u confused cause you said the same thing twice"

Ignoring the child-like behavior of tweeters, this actually is an interesting question that I had to think about for a moment: Can the idea of objects separating by density be used to explain gravity without invoking gravity? And, I don't think it can. For example, let's simply take a ton of lead and a ton of helium. Assuming you've heard that one and know that one ton of something weighs the same as one ton of another thing (after the old joke, "Which weighs more, a ton of bricks or a ton of lead?"), then we can ask why the ton of lead will fall to the floor while a ton of helium gas will rise toward the ceiling.

The only reason this happens is because of gravity. The less dense material rises because the denser material - in this case air relative to helium - is pulled more towards the center of the planet because of the greater mass which translates to more gravity. If there were no gravity, this wouldn't happen.

Astronauts have shown this on the International Space Station many times, such as by releasing a small ball of water in mid-air. It just stays there or floats about, it doesn't go immediately rushing down relative to the camera, it just stays there because there's a microgravity environment. So even though I think we would all agree that water is still denser than air regardless of whether you're in space or not, that kind of experiment shows that objects of different density only fall into a column arranged by density when acted on by the force of gravity.

In fact, we can go to basic physics for that, too, with Newton's First Law of Motion can be colloquially summarized as, objects in motion (or rest) stay in motion (or rest) unless acted on by an external force. Density is not a force, it's a property of matter. In order for a ton of lead to fall to the ground if I release it, that lead must be acted on by a force -- gravity.

Pointed Shadows

Moving on from B.o.B., another set of flat Earth proponents said that the shadow of the moon on Earth proves the standard model is wrong. It doesn't prove Earth is flat, nor does it prove Earth isn't round, but they think it does. In that sense, it falls very much under the classic young-Earth creationist argument that if you think you have disproven a standard model, then your model is the only one that can possibly be correct.

The idea of the shadows goes like this: If the Moon is 25% of the size of Earth, then the path of totality should be 25% the size of Earth. It shouldn't be a narrow band because shadows don't form points, the rays should all be parallel.

This might seem to make sense at first, but the mainstream answer lies in approximations not being 100% reality. In our normal, everyday life, all light from the sun that hits our planet is coming at us straight and parallel along a line directly connecting the midpoint of the sun with the midpoint of the planet. But that's not exactly true.

Light streams out in all directions from each point on the surface of the sun. That means that you could be getting a light ray at this moment from the left side or the right side, the top side or the bottom side. The sun is a disk, it has a finite size in our sky, and we get light rays from all parts of it. If we didn't, then we wouldn't see it as a disk, we would just see the shape as from where we get light.

When the moon passes in front of the sun as seen from a location on Earth, one must ask what "part" of the sun is it passing in front of because both are spheres -- or disks, or whatever, it actually doesn't matter in this case to explain basic optics.

Regardless of the shape, what's important is that the sun is still large, the moon small, and the sun far away. You can do the experiment yourself and trace out light rays from a large sun, with a small moon between it and Earth. If your model is roughly to scale, which would require a big sheet of paper, what you'll find is that a lot of Earth's dayside will still be able to see all parts of the sun's disk. A small part of Earth will see light blocked by the moon from SOME parts of the sun, but it will be able to see light from some other parts of the sun. But, there will be a small part of Earth that will not have any pathway to see the sun because the moon blocks light from all angles of the sun's disk.

Incidentally, if the moon were farther away as it sometimes is in its orbit, no spot on Earth will be fully within the moon's shadow -- there will always be some straight path around the moon to get to the sun from any location on the dayside of the planet. In that case, we have an annular eclipse. Or, if the moon is off to one side, a partial eclipse.

Young-Earth Creationists Again

Finally, I shouldn't leave this topic without again giving credit where credit is due, to the Creation Ministries International which also put up a post explaining how eclipses don't prove Earth is flat.

They pointed out two things that I think are worth mentioning, one because I somehow missed the obvious implication, and the other because they did a bit of math.

First up is going back to B.o.B.'s first and second tweets, where the clear implication is that we don't see the moon leading up to an eclipse, so how do we know that's what's causing the eclipse. The answer is obvious: We can see the moon a day before and a day after. We can connect the dots. The connection goes through the sun. This works all other nights, why should we assume the moon makes a hop, skip, and a jump over the sun in that particular instance?

The second is the math. They showed that based on the observable fact of how large the path of totality is, IF you use the number of many flatEarthers today that the sun is only 5000 km away (3000 miles), then the moon can only be 0.13 km across and 12.5 km away. As in, 427 ft across and 7.5 miles away. That would mean that we can easily fly above the moon in airplanes, because it's only 39,600 ft up. So when you hit that cruising altitude of 40k ft, you're above the moon. And yet, at least from my own anecdote, I have seen the moon above me, not below me, while flying at such a cruising altitude.

Part 2 Wrap-Up

This Part 2 is a bit shorter than Part 1, but I don't think it needs to be any longer, and I don't know about you, but I can't take too much flat Earth stuff in one sitting. To borrow again from the CMI post, I think this is something that you should remember: "Friends, this is not true! Don't get sucked into the flat-earth nonsense."

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