# Proposed experiment measuring Doppler shift of the sun on a flat earth model

#### Davy Stone

##### New Member
I had an idea for an experiment that would either provide evidence for the flat earth model or the heliocentric model depending on the results.

Using the flat earth model, the sun orbits a circle above the earth. The circle should have the greatest diameter during the Summer Solstice, and I believe that diameter is approximately 11,500 miles (correct me if I'm mistaken).

Using basic geometry the sun would travel 36,110 (11,500 * 3.14) miles in a 24 hour period resulting in a speed of 1504.58 mph or 672.60 meters/sec.

I think some calculus is required to determine the actual speed that the sun would be moving away or toward an observer in an arc, but I imagine it would not be much less that the speed I calculated.

That speed should be enough to measure a small amount of red or blue shift in light coming from the sun.
Does anyone know if an experiment like this has been performed? If so can you please provide a link? Or is my idea faulty on some level?

I don't prescribe to the flat earth theory and I think the results of this experiment would be worth looking into, if only to debunk that aspect of the flat earth model. And it wold definitely raise some questions if a significant shift were measured.

#### Mick West

Staff member
The problem with that is the Flat Earther's would simply claim the observed doppler effect is due to the movement of the nearby sun moving in a circle above the flat Earth. Since their model is already physically impossible to reconcile with existing observations, then adding another impossible observation to it will only make it stronger.

Here at Metabunk we focus in debunking specific claims of evidence. We don't try to prove or disprove a particular theory, which is what you are trying to do here.

That said, if you can create a simple experiment that everyone can do at home, that would help answer the FE evidence claim that there are no such experiments. Unfortunately I don't think measuring the doppler shift of the sun is something many people can do.

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#### Chew

##### Senior Member.
How did you derive an 11,500 mile circle?

Most flat earthers claim the diameter of the flat earth is equal to the circumference of the spherical earth (24,856 statute miles). The length of a degree of longitude on the flat earth increases linearly southward from the north pole. The length of a degree of longitude on the flat earth is equal to (90°-latitude°)/180° * 216.92 statute miles (southern latitudes are negative numbers). During the northern hemisphere summer, the Sun will travel in a circle with a circumference of (90° - 23.5°)/180° * 216.92 smi * 360° = 28,850.36 smi.

You won't need calculus to compute the expected Doppler shift; just a bunch of plane trigonometry.

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#### Davy Stone

##### New Member
How did you derive an 11,500 mile circle?

Most flat earthers claim the diameter of the flat earth is equal to the circumference of the spherical earth (24,856 statute miles). The length of a degree of longitude on the flat earth increases linearly southward from the north pole. The length of a degree of longitude on the flat earth is equal to (90°-latitude°)/180° * 216.92 statute miles (southern latitudes are negative numbers). During the northern hemisphere summer, the Sun will travel in a circle with a circumference of (90° - 23.5°)/180° * 216.92 smi * 360° = 28,850.36 smi.

You won't need calculus to compute the expected Doppler shift; just a bunch of plane trigonometry.

Actually, I have struggled to find the exact figure FEers use as the diameter of the sun's orbit, and I have been unable to find a diagram that shows it, but I have read several of them claim it to be around 11,500 miles.

I never considered that the orbital path of the sun on the flat earth model would be about the same distance as the circumference of the spherical earth. For some reason I had it in my head that the flat earth plane also had a circumference of about 25,000 miles.

In any case, if the sun travels in an even larger circle, then the velocity would be even greater: 12,897 meters/sec based on your math, which would result in even greater doppler effect.

The reason I suspected calculus would be required to determine the true velocity is because as soon as the sun passes overhead, it would not be moving directly away from the observer in a straight line, but in a circular path.

At any rate, Mick is right that most people do not own spectrometers to actually perform the measurement, which is unfortunate because I predict the doppler effect would be measured to be far less than the model of a flat earth would suggest.

#### Chew

##### Senior Member.
12,897 meters/sec based on your math,

537 m/s. (You forgot to divide by 24 hours.)

The reason I suspected calculus would be required to determine the true velocity is because as soon as the sun passes overhead, it would not be moving directly away from the observer in a straight line, but in a circular path.

Yes, it will be a circular path but given the Doppler shift will be measured at a single instant in time all you need is the velocity in your line of sight at that one instant. Plane trig is all that is required.

At any rate, Mick is right that most people do not own spectrometers to actually perform the measurement, which is unfortunate because I predict the doppler effect would be measured to be far less than the model of a flat earth would suggest.

A more convincing experiment would be to take frequent pictures of the Sun throughout the day, zoomed in with a shade over the lens so the disc of the Sun is clearly visible, so people can see the size of the Sun doesn't change as it must if it were circling over a flat earth at 3000 miles.

#### Henk001

##### Senior Member.
In fact the experiment is being carried out almost continiously, because the spectrum of the sun has been and is being recorded very often on very different times and dates, and studied very frequently, with very precise measurements . So if any doppler shift were visible it should have been (unintentionally) detected long time ago.

#### Mick West

Staff member
In fact the experiment is being carried out almost continiously, because the spectrum of the sun has been and is being recorded very often on very different times and dates, and studied very frequently, with very precise measurements . So if any doppler shift were visible it should have been (unintentionally) detected long time ago.

Sure, but there are thousands of scientific observations that only make sense in a round Earth model, they problem here is that they are opaque and inaccessible to the believer. The basis of their argument is that they themselves cannot personally verify the claims of "scientists"

#### Whitebeard

##### Senior Member.
The basis of their argument is that they themselves cannot personally verify the claims of "scientists"
Despite the fact that thousands of amateur astronomers and casually interested stargazers do so everyday. In fact many astronomers use amateur data collection for surveys and on going observation. Like with the Charlie Bates Solar Project for example. In fact astronomy is perhaps the last major field of science where the interested man in the street can work on cutting edge research, and can help contribute to a major discovery or break through.

#### Mick West

Staff member
Despite the fact that thousands of amateur astronomers and casually interested stargazers do so everyday.

Indeed, and I think that some observation of the sun, stars, and moon would be enough to convince any reasonable person. It does, however, require a certain amount of spatial understanding.