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Topics - Bobby Shafto

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21
Flat Earth Theory / Angle of Sunrise/Sunset
« on: October 01, 2018, 03:11:03 AM »


This is a New Zealand sunrise.

I've never seen the sun rise like this. I've been to Australia (and Argentina, Chile) but I never paid attention to how the sun rises or sets there.)  I'm used to seeing sunrises and sunsets angle to the right/north. 

Stellarium models sunset at my current latitude north of the equator like this, matching sunsets I routinely observe:



The same day of the year, Stellarium shows an Auckland, New Zealand sunset angling like the video above:



This is explicable with globe earth/distant sun mechanics. I don't know how this would work with a sun circling overhead a flat earth. Could this be a feature for zetetically determining whether we live on a globe or a not-globe earth?

(I believe I raised this point early on, or it might have been on the other community board. But I don't think it was every discussed. Has it? Is it addressed in any flat earth (or non-globe earth) media?)

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Edit: I did ask this on this board back in May. Never got a response and I forgot about it. Administration can combine the two topics. I won't complain.


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Also: globe-defender Walter Bislin created a flat earth model based on a dome over a monopole earth, and had to add a 2-dimensional (vertical and horizontal) light-bending parameter to make it work.



22
Flat Earth Investigations / Gambling on Sunset
« on: September 29, 2018, 10:53:09 PM »
I recently discovered that UCSD has something called the High Performance Wireless Research & Education Network (HPWREN) that includes web cameras mounted on the masts around the local San Diego county high points. I started checking them regularly for visibility before decisions whether or not to go out for any observations. I didn't consider the resolution sufficient for what I've been trying to do in investigating flat vs. globe earth.

But I happened to catch the moon setting this morning on one of the camera feeds, which gave me the idea that maybe it might capture the sunset and let us gauge where the horizon is with respect to level. But rather than collect the imagery and try to assess it, I thought it might be my interesting to make some predictions beforehand and THEN see how it played out.




This is just a rough cut, but according to the HPWREN web site, and in looking at the views from other cameras, I deduce that the western facing camera is at an elevation of ~1600'. Mt Soledad in La Jolla is 822' at  distance of 66,222' away, and so that gives me an index line: 0.7° declined below level sight (we'll go with a flat earth measure; on a globe with std refraction, eye level would be 0.1° higher).

On a globe, instead of the horizon being at eye level, it should be declined 0.65° from that 1600' vantage point. In a bit of serendipity, Mt. Soledad summit seems to coincide with the globe "horizon," below the FE eye level "horizon".

How to gauge the angular dimension? That nearby water tank is 32' from ground to edge of the domed top. Working out the trig (I forget the distance off hand), it's about 0.5°. So that provides a pixel/degree ratio basis, and using that is how I can place the eye-level line above the Mt. Soledad summit line (and projected globe earth horizon line).

Does that follow? The sun is about 0.5° in angular diameter too, but I don't expect we'll see its actual size without a filter. The haze low on the western horizon may filter the sun enough to see it as an orb.

Looking at TimeandDate, the sun should set at 6:35PM on the 267° azimuth. It looks to me like the camera is oriented on 270°, and that seemed to be corroborated by the earlier moonset bearing. So I placed an arrow where I think the sun will set.

I'd like to refine these lines and measures using the larger resolution photo instead of this reduced image (reduced for the purpose of posting it inline and not wrecking the page). But I wanted to get this posted now, just in case I don't get back to it before sunset.

Anyone can check and see if the prediction was close. Will the sun appear to set below the eye level line? Will the time and bearing of TimeandDate.com match what I'm predicting?

Here's the direct link to the web cam. Under 3 hours to sunset.


Edit: I see the sun is already in view, and now see that the disc is being eclipsed. I don't know if that will remain in place all the way through to sunset.

And it's looking grim for my globe estimate. Sure looks like the horizon is appearing to be raised above the Soledad summit, just about the level I figured was FE eye level...though the image below is cropped from the original at double the resolution than my annotated one above. Nevertheless, my estimate of globe earth horizon is looking wrong. Depends on the haze.




Either my geometry/trig was way off or that sun eclipsing disk is well greater that 0.53°.

Update #2:
I don't. GoogleEarth depicts the globe horizon just barely cresting the summit of Mt Soledad when height is set at 1600' from the Black Mtn view point.




Update #3:
Still looking like horizon is around 0.5° above Mt. Soledad summit. (Large JPG file, annotated)


Update #4:
Raw image at sunset.  Will assess tomorrow, but anyone can do it.

Update #5:
Looking at this morning's camera feed and at last night's file capture of sunset, I find myself asking lots of questions. When I initiated this topic, I was nervous because my globe earth calculation of where the horizon should be compared with where it appeared to be was so different. But from lower elevations, I'm well-familiar with what the atmospheric haze and marine layer can do to make the actual horizon difficult to see. But seeing from the vantage point of 1600' I wasn't so sure. And as I watched the sun illuminate the ocean and appear to make the horizon distinguishable, I thought I was going to have to eat my hat and score one for flat earth. 

It shouldn't have been a surprise to me, but it was when I checked the archived picture after sunset -- I missed the actual event live -- and saw the sun setting below the apparent horizon. I still have to mark it up and measure, but just eyeballing it, it sure looks close to the prediction.

The azimuth was way off from predicted though, but that's just my error since I was guessing that the camera was pointed due west. I checked the bearing line with GoogleEarth and the sun DID set on a bearing of 267°. So now I know how the camera is oriented.

The time was off as well, by a couple of minutes. But I forgot that from a higher elevation the time, of course, will slew later. Local hot air balloons give their customers multiple sunset viewings by climbing through higher altitudes. I should have known the time of sunset would be later.

But that horizon: even this morning, looking at the feed, I could swear the horizon is higher.

And looking at last night's shot, the sun is setting on a bearing line just about in line with the northern tip of San Clemente Island, but I can't detect any hint of the island in the image. MAYBE there's a tip of Mt Thirst poking up above the marine layer. Or, I might be just trying to see something that isn't there.

23
Edit: Link fix

This topic was moved to Angry Ranting with the justification "Complaints about how you totally don't like FET don't belong in the upper."

I do not consider this a proper justification. I pondered how to present this challenge to the Bishop Experiment, both wanting to highlight my own observational testing experience in contradiction and asking for more detail on how to replicate a observation test that appears in the TFES wiki.

I request a review of the moderating decision and an appeal to have the topic moved back to the Flat Earth Theory topic board.

I've been told by another moderator that the S&C forum is where to air these types of grievances, but if this is not the proper means to submit a request such as this, please let me know the correct avenue.


24
Flat Earth Theory / Equinox and the Bi-Polar Model of Flat Earth
« on: September 23, 2018, 04:24:28 PM »
The sun crossed the equator yesterday somewhere over Indonesia, passing from north to south.

According to the bi-polar model, the sun will spend the next 6 months rotating around the south pole:



If true, wouldn't that mean that, from my vantage point 33° north of the equator (Southern California) I should witness a shift in the sun's trajectory during sunset?

Top image: before Autumnal Equinox
Bottom image: after Autumnal Equinox



Even more dramatically, the sun should starting setting in the S or SSW. This doesn't happen, of course. Am I misinterpreting the bi-polar model or does this show the bi-polar model can't be right?  (I found an old topic on this subject that didn't address this question, and rather than dredge that one up, I started a new topic. I trust that's okay.)

25
Flat Earth Theory / Viewing Brighton Seafront from Worthing
« on: September 18, 2018, 01:18:18 AM »
Video author: Dr. John D.
Title: Viewing Brighton Seafront from Worthing with a Nikon P510



A mirrored version of this was posted on the Flat Earth Media board, but I'd like to talk about it.

This slide in particular:



Light is not refracted downward? Over the sea? At night? This isn't right.

Even with a stable air mass, with standard temperature gradient, an atmoSPHERE will refract light downward. That's typical and to be expected. It's not a peculiar occurrence that requires "specialized" environmental conditions.

Maybe in an atmoPLANE that would be true. But he's talking about "according to the Sphere/Globe earth model," and in that model a standard lapse rate in temperature/pressure/humidity WILL refract light downward.

In fact, evidence to answer Dr. John's of "photographic proof" is present within his own imagery.



Note the "compression" of the lower floors of the building in the foreground of Sussex Heights. That's indicative of a greater refractive index at the lower angles than at the higher elevation. 



26
Flat Earth Theory / Viewing Mt Helix from Cabrillo Point 16.2 miles
« on: September 16, 2018, 04:32:23 PM »
Post #1
Help me with my math.

363' observation point.
1372' target.
16.2 mile distance.

What's the elevation angle -- to the nearest tenth of a degree -- above level (eye level) for a flat earth and for a globe earth (r=3959 miles); no refraction?

I got:

+0.7° for flat earth.
+0.6° for a globe earth.

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Post #2

0.1° may be too small an increment to measure with confidence using Theodolite app.

Despite a no-refraction 175' "drop" difference between a flat and globe earth over 16.2 miles,  the angular delta may not be large enough to distinguish without more precise tools.

Could adding an 8-12x telephoto capability to the phone focal length help distinguish a vertical difference if 0.1°?

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Post #3

I think enough eyes have seen this, so I'm going to assume there are no corrections to the geometry.

Here are the geographic details:
Observation Point: Cabrillo National Monument
32.674005, -117.238946

Target Objective: Mount Helix Cross
32.767044, -116.983436

Last week, I noticed I could see the cross on Mt. Helix from a San Diego bay overlook near where I work. I can't take photographs from there, but I can go out to the Cabrillo Monument; and so I played with Google Earth and did the math to try to predict what the elevation above eye the cross should be from that observation point at the end of Point Loma.

I'd hoped to make predictions first before taking a sighting to avoid after-the-fact calculations, which can sometimes be skewed to match what is observed to what one wants to see.

I'm going to work with the Theodolite app to calibrate it and see if I can repeatedly, consistently take measurements to within 0.1°. I've tried this taking level sightings at the Coronado Islands 20 miles away, but the elevation data on the islands is much less certain than the ground elevation of Mt. Helix summit.

I'm also going to see if a telephoto multiplier lens for a smart phone will enhance the sighting at all.

Prediction going in is the Helix cross will be elevated +0.7° if earth is flat. +0.6° if earth is a globe.  Hoping I can do this in the mornings over the course of several days. I'll also thought it might be good to take some time lapse images for 15 minutes before and after each sighting to check for "Skunk Bay" -like dynamic atmospheric conditions.

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EDIT: Merged several posts to make OP adequate for upper fora. ~junker

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Post #4

Too much haze (smog) today for Theodolite/Phone camera, and I'm resigned to the fact that Theodolite app is just not up to the task. The cross hair line itself is 0.1° thick. And with needing to distinguish between 5.8° and 6.8°, getting level at 0.0° is critical. Even with repeated calibration, I felt the tool was inconsistent:


I was able to cut through the haze with my camera and, with a little color and clarity adjustment, was able to get a decent shot of Mt. Helix. (I'll link to the original image file since it's large.)

Could analyze angles and elevations using the Hilton Bayside tower in the foreground as a gauge. Has to be better than Theodolite, which just isn't cut out for what I set out to do here.

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Post #5

Cropped from original; resolution unchanged:



Can use this to figure vertical angle above level to Mt Helix summit (foot of the Helix cross). Need to find level first (different for FE and GE).

Photo taken from 363' elevation using a tripod set 4' high for a total of 367'
The Hilton, 26,739 feet away, is recorded as 385' tall on about 8' elevation (avg).


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Post #6

Calculating elevation angles above horizontal level for both Mt. Helix and Viejas Mountain, based on the measurements of the San Diego Hilton Bayfront tower:




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Post #7

Results recap:


The FE/GE "contest" starts to show more clearly with the unanticipated inclusion of Viejas. Helix measurements are too close to call and could easily be within margins of error.

I'll keep observing and measuring to see if different days/conditions produce different results; probably won't be able to bracket observations with time lapse imagery like I had hoped.

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Post #8

Tried again today...same spot...earlier in the day this time, but more haze/smog trapped in the basin than yesterday.

Widened the field of view to capture Cuyamaca Peak and add that to measurement. GE (with standard 7/6 refraction) consistently undershoots while FE calculation overshoot increases with range.

Having to take photo with heavy color processing to create contrast due to haze. Lots of blue. But otherwise, unaltered. Link to annotated photo in native 4000x2248 resolution is 2.2MB.

27
Flat Earth Theory / IR Video from FL310 -> 500 mile visibility?
« on: September 03, 2018, 12:07:41 AM »
New video upload from JTolen Media 1:



Most of the footage is raw from left window seat of a LAX-MCO flight while passing over Arizona and New Mexico, view northward.

The intro is where the analysis is presented, along with a short evangelical statement regarding the flat earth movement. This will accumulate the usual accolades from the flat earth community, and I thought of posting it in the Flat Earth Medium forum. But I'd like to discuss it, so I'll post it here. I'm hoping JT will visit to answer some questions.

If he does show, I ask that the skeptics and naysayers of flat earth play nice. I'd really like to encourage YouTube video publishers to discuss their postings here. I know there's a view that The Flat Earth Society is a disinformation effort, but that's between the factions of flat earthers. I'd like to have a place other than YouTube comment section to  encourage discussion, debate, and critiques of these videos, including those defending the globe earth.

I really like this Infrared approach to imagery capture and wish I had the equipment to do the same. But I'm not willing to risk my modifying my cameras so I'm left to examining the products folks like JT are posting. 

28
Flat Earth Theory / Atmospheric Refraction and the Sinking Ship Effect
« on: August 31, 2018, 02:55:01 AM »
I'd like to kick this off with a nice time lapse of a cold Montana vista. Whether the earth is flat or convex, this is real and shows how dynamic the atmosphere can be and how it can alter what we see.

Before we dive into potentially contentious discussion on the whys and what fors, let's just relax and enjoy the art of nature:

(Turn sound on if able. The audio score enhances the visuals. Music is "Morning Sun" by Draum)



And one of Pacific sunset with an elevated inversion, creating a superior mirage affecting the sun and one of the Farallon Islands, off the San Francisco coast. Music is instrumental version of "Sally" by Bertysolo.


29
Flat Earth Theory / Flat Earth Model
« on: August 25, 2018, 02:14:05 AM »
This may very well be the best flat earth model in existence, even if it was written by a globe earth proponent.

It certainly can't address all of the variations of the flat earth (esp. JRowe's DET), but what I thought might be most fascinating is its "light bending" parameter that can be used to match some observations with the mechanics of a potential flat earth (with a dome). He says that there is no scientific explanation for the light bending, but Electromagnetic Accelerator Theory posited by the Flat Earth Society might be model-able with this tool. You just have to tinker with the inputs to get the light to curve the way EAT hypothesizes.

Read the conclusion and the purpose to understand why he created this model, but despite his motives, I think it finally presents a workable model that has been lacking in the FE library of tools and illustrations. I'd be very interested to hear FE critiques:

http://walter.bislins.ch/bloge/index.asp?page=Flat+Earth+Dome+Model

30
Flat Earth Theory / How to Distinguish Flat Earth EAT from Convex Earth
« on: August 23, 2018, 07:49:35 PM »
I've been wondering for awhile how EAT on a flat earth would be distinguishable from orthodox globe earth light.

While reading up on super-refraction, it occurred to me that EAT would be manifest by the sun becoming elongated as its elevation decreased since light from the sun's upper limb would be bent less than the lower limb.

We often see the opposite of this at sunrise and sunset when the sun can appear squashed due to refraction bending light toward the earth.

If EAT were real, the sun would not remain a circle/orb throughout the day. It would exhibit stretching in the vertical as it dropped toward the horizon.

No?

31
Flat Earth Theory / Flat vs. Sphere Challenge (Group Effort)
« on: August 19, 2018, 10:07:53 PM »
First step (if possible) is to fill out this table:



We all know how to calculate (or how to use online calculators) to come up with how much of a target height will be hidden on a sphere of earth's claimed radius, not accounting for surface irregularities or atmospheric effects on optics.  I used a popular calculator found on GitHub to fill out the table for a spherical earth.

What I don't know for sure is how to fill out the flat earth column. I would be inclined to put 0 all the way down, but I don't want to presume and potentially skew the challenge. So I ask any willing flat earth advocate (not "globetards" playing devil's advocate) to step forward and propose values for the flat earth column.

We are to ignore atmospheric effects like refraction, which has been disparaged as a "magic wand" used to salvage spherical calculations.

Step 2 will be to examine a series of images taken of a target at these ranges/heights and see if we can assess actual hidden/not hidden values. I can promise up front that the values in the spherical earth column above will not match what we will deduce from the images. Since I have no values for the flat earth column, I can't yet make the same declaration for that camp, but I predict that whatever values flat earth calculation might produce will likely be "ballpark" and not perfectly match what we find in the images either. That's okay.

Step 3 will likely and unavoidably occur coincident with the process of Step 2 since it is human nature to want to analyze with an eye on the desired conclusion. But, if we can, the step will be to assess whether the evidence is more supportive of a flat earth of FET (flat earth theory) or a spherical earth of the size that is the consensus in RET (round earth theory). 

Finally -- and since I predict the measured/derived values will be less than Step 1 calculated values of RET's but greater than FET's, we can then debate using "magic wands" to argue for adjustments that could swing the raw values closer to your supported model and away from the opposing model.  That is if we actually get that far.

This might not even get out of the blocks.  To do that, we need some flat earth numbers to fill in the table.  Anyone?

32
Flat Earth Theory / Eastern Storm Clouds After Western Sunset
« on: August 17, 2018, 03:46:30 AM »
10 minutes after ground level sunset, thunderstorm build up 40-50 miles to the east brilliantly lit by the sun.


30 minutes after sunset, still picking up the western light:


I don't understand how a spotlight sun over a flat earth can make this happen. For me, this is just another observable phenomenon that is explicable by a spinning globe earth.

33
Tom Bishop posted another interesting video of an investigator using IR photography to view and analyze long range viewing:



FE Photographer believes he's captured no-curve imagery. But has he?



Camera elevation: 17 feet (Bayview Park on Padilla Bay)
Distance: 19.5 miles (to Clark Island, San Juan Islands)



Should Clark Island be hidden if the earth is a globe?

34
Flat Earth Media / Chicago Skyline: Mirage & Looming
« on: August 12, 2018, 02:31:44 PM »
From 2 years ago, how atmospheric effects can change what's visible of the Chicago skyline looking across 50 miles of Lake Michigan:


35
Flat Earth Theory / Did FE YouTuber Unwittingly Provide RE Evidence?
« on: August 03, 2018, 07:40:26 PM »
I just want to comment that Bobby seemed to have spent some time looking at something from the videos, which he deleted. I thought about it and had something to respond with. I am more than happy to look at it with him if he were to repost it in the main forums.

You posted a link to this video:



I posted that that YouTuber was wrong in his analysis of his evidence:



He claimed 10,800' Mt San Jacinto shouldn't be visible from a 150' high viewpoint in Malibu, CA, 117 miles away if the earth is curved.
I claim it should be, and his imaging -- despite his accompanying narrative to the contrary -- shows what is expected on a curved earth and not a flat earth.

The graphic I posted was in error. For that reason, and because of the request not to debate in the Media forum, I deleted it. But I'm more than open to discuss it, Tom.

36
Flat Earth Theory / Dual Earth Theory - The Moon
« on: July 28, 2018, 04:06:09 PM »
I'd like to split a discussion off from this other thread since it's quite the tangent from that original topic.

JRowe has a unique version of a flat earth model that he's dubbed Dual Earth Theory. I first became aware of this when he introduced an alternative theory for explaining the phases of the moon in another discussion topic. There we wrangled over whether or not we see the same "face" of the moon as it goes through it's lunar phase cycle.

In the Dual Earth Model, the moon (like all celestial bodies) is a "star," emanating its own light rather than reflecting it. It is like a rocky canister, encapsulating molten metal that acts akin to a spotlight:



It rotates as it circles the sun, projecting an image of the lit "face" of the moon on a dome over the twin flat hemiplanes of earth. It is this rotation, and not the relative positions of the  sun and moon and the angle on which the sunlight is reflected off the moon's surface that is responsible for the observation of the moon's phases from earth. Something like this:



Quote from DET Overview:
Quote
The moon is the final such entity. The same basic principles hold [as for the sun], though it doesn't exist in the center. Instead, it rotates around the Sun, as well as on its own [axis][/i]: hence the phases. As it rotates, it will have its image projected by the same flow of aether, to the top and bottom [/i][hemiplanes][/i]. Sometimes this will be a full moon, and sometimes less of the face will be visible. Common belief is that the same face of the moon faces us at all times. this is an optical illusion: any notable features will still be visible on the tilted moon, so we will certainly observe some similarities. The moon is too far away for us to say anything more. [/i]

This DET claim was challenged in the Full Moon Impossible topic when several members presented images of a moon exhibiting what is known as "earthshine," like:




And with time lapse image of the moon going through its phases:


Using Stellarium (equatorial mount, earth rendered invisible, atmosphere removed), I captured a similar sequence of images of the moon's predicted image over the next month, starting with last night's full moon:


The above is from a simulation, and the animated image directly preceding is claimed to have been from the NASA Lunar Reconnaissance Orbiter (LRO) satellite. As such, both might be rejected if presented as contrary evidence to the DET claim due to skepticism or disparagement of the sources.

So I propose a direct observation of the moon over the next 28 days (or as many of those days as the moon is visible), capturing images of the moon to see if the terminator of the moon does, in fact, sweep over a non-rotating face or if the moon rotates as stated by DET, the phases of the moon are the result of rotation of a spotlight. I will take it upon myself to capture images from my vantage point (San Diego), but I welcome the participation of others. Care should be taken to get enough detail and get the right exposure to capture the moon's surface detail so that we can determine if the face is rotating away/toward the earth or always facing the earth.

Any "earthshine" images showing moon features in shadow (or alternatively, where the rocky encasement theorized by DET should be), would be a bonus.







37
Flat Earth Theory / Photo Analysis - Sea Horizon
« on: July 04, 2018, 02:29:05 PM »
I would like to try to apply flat earth theories to analyze a couple of photos I took yesterday. This is from the first photo, taken from Cabrillo Point in San Diego, looking WSW from https://goo.gl/maps/YnzAo9batsT2



Date/Time
July 3rd, 2018; 10:55 PDT

Weather Conditions
air temperature 70°
water temperature 68°
humidity 66%
dew point 58°
visibility 10+ miles
onshore wind ~5kts
mixed wind/south ground swell 1-3'

Location
N32°40'30.2"
W117°14'46.4"
elevation ~100'
Viewing azimuth WSE ~250°

Camera
Canon PowerShot SX5 HS
1/320 sec; f/8; 215mm
ISO 100
4000x2248 resolution
Cropped to 1000x562
Contrast/color adjusted

Comments: I didn't notice this with the naked eye at first. It was only while panning the horizon at my greatest analog zoom that I saw it. Looked a little like a city skyline peeking over the horizon, but it's actually a loaded container ship some distance off the Southern California coast.

Why does it look like this?

38
Flat Earth Theory / Full Moon Impossible on Flat Earth?
« on: June 29, 2018, 05:57:20 PM »
Open topic (of course) but directed toward Tom Bishop (who asked that this be split off to a separate topic).

In answering explanations for how a full moon is possible in the globe earth model, you (Tom) said:

If you are making your claim without evidence then we can discard it without evidence.

Fair enough. Can we discard these claims then that serve as explanatory claims for a full moon on a flat earth?

TFES Wiki

Quote
"The moon is a sphere. It has a diameter of 32 miles and is located approximately 3000 miles above the surface of the earth."

Quote
"The lunar phases vary cyclically according to the changing geometry of the Moon and Sun, which are constantly wobbling up and down and exchange altitudes as they rotate around the North Pole."

Quote
"When the moon is above the altitude of the sun the moon is fully lit and a Full Moon occurs."

Show me evidence for how a sun can illuminate a moon, both of which are above the surface plane of the earth such that a full moon ("bottom" of the moon, remember) can be seen from earth.

Can you model (or just diagram) that and show me evidence of how that can work?

39
Flat Earth Theory / A Horizon Sighting Survey
« on: June 19, 2018, 06:52:40 PM »
In the attached image, there appears to be a clear, sharp horizon between earth and sky (see red line index drawn on the right hand side of the picture).

Is this the "true horizon?" Or does it just appear to be a horizon and the actual horizon is actually higher or lower? Is it even possible to tell?

I'm not planning on lecturing, as if I know the answer. I do have an answer I think is right, but I'd like to see what others think first.  I'm just going to set this to run for a day, after which I'd like to talk about it.

40
Flat Earth Theory / How Far Away is the Horizon?
« on: May 23, 2018, 07:14:07 PM »
I've been stumbling over this, thought I'd figured it out, but now I'm back to confused.

I know how to calculate an approximate distance to a visual (and a radar) horizon on a globe earth if accounting for atmospheric effects.
What I don't know is how to interpret Rowbotham's explanation for horizon and horizon phenomenon in a way to calculate or even estimate a distance to a horizon plane.

There are diagrams in Earth Not a Globe like this:



...where the ground plane appears to slope upward to eye-level and then level off.





That point of H, where the slope changes from rising to level, parallel (coincident) with the level plane of the eye, is what EnaG claims is the horizon. I understand that. I even understand the explanation for why things further away than H can still be seen since H isn't a vanishing point. It's a line that is the edge of a plane, beyond which more distant things can still be seen (though smaller and smaller and ultimately converging with that edge (unless obscured by atmosphere or other other reasons first).

But what I can't grasp is how to figure where H is away from the observer. Tom Bishop might have misspoken when he wrote, "The horizon is one of the the furthest thing on earth that can be measured," but that has stuck with me and I've tried to work it out for myself, reading and re-reading the pertinent sections of EnaG. I'm just not getting it.

H is obviously dependent on the height of the viewer's eyes (or camera lens), as is true for a globe earth. But I can use geometry/trigonometry to calculate where the non-level eye line of the observer is tangent to the convex surface of the globe. And I can make adjustments or figure ranges of the distance to H to account for refractions. I can do all that on a globe.

What I can't resolve is how to do that given the conventional explanation for H in a flat earth model, where perspective plays such an important role.

I thought maybe Rowbotham's H might be calculated from the claimed limit of angular resolution of the human eye being 1 arcminute. But that's working out to be some crazy numbers, never witnessed or recorded. Diagrams and explanations and analogies are fine for conveying the concept, and I think I grasp the concept of what the horizon is for flat earth. But is there a way to figure how far away a horizon is in a flat earth model for a given height of the observer?

Basically, when do you know you are seeing a "true horizon" and, given that, how far away is it?

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