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Offline Bobby Shafto

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This is a frame grape from a video I took Sunday from Mt Soledad in La Jolla looking south across Point Loma toward the Mexican Coronado Islands, about 30 miles away. That's South Coronado Island. It had been super clear on Saturday, but Sunday the haze had returned, so I hope to get back to this same spot soon on a day when there is a sharp horizon of blue sky against the sea. 

My hope is that this vista will provide evidence of either flatness or convexity. If flat, the horizon should, on clear days, appear near the level of the South Coronado Island summit.  Thing is, I don't know for sure what that elevation is.  Google Earth seems to believe it's 580', but other sources indicate it's over 700' high.

I can also make out the Old Point Loma Lighthouse. Google Earth puts the tip of the cupola at around 465-467', which seems right.

My viewing elevation, with tripod height, was about 770 ft. If I bring out eye-leveling tools, where will eye level be? Will that S. Coronado island summit be near eye level?

Anyone care to join me in analyzing and researching these identifiable points before I'm afforded a clear day on which I can get back there to shoot the horizon with my level tools?  I think I'd like to compose a video of the analysis and the process of collecting the data, which I'll post whether it suggests -- I avoid saying "prove" -- a flat earth or a globe earth. If that's flat or even flat-ish, I'll admit it.

Edit: Great visibility on New Years Day


« Last Edit: January 02, 2019, 05:44:56 PM by Bobby Shafto »

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Offline Bobby Shafto

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Here is a photo of South Coronado Island taken from the south looking north.



I'm having trouble verifying the highest elevation on the island. Wikipedia lists 722' (220m),
But on the same page is a topo map with contour lines only going up to 180-200m.
Google Earth depicts the north peak at 488' (149m) and the south peak at 580' (177m).
Another topographical resource has the north peak at 515' (157m) and the south peak at 654' (199m)
Nautical chart only lists the height of the beacon on the north peak at 672' (205m)

Clearly, the southern peak is higher than the northern peak, as is evident in my picture, which was taken from an elevation of 770'. So flat or curved, even at highest figure, South Coronado island would be below eye level. The only question is "how much below?"

But the horizon is well below that in both the uncertain hazy image and in the clear image. In fact, the horizon appears at the same angular location in both images. I intend on continuing to collect images of this view from this same location, so we'll be able to see how much variation there is in the horizon.

However, moving on from that, where IS "eye level" in this image? Google Earth seems to me to be flawed. I know Google has errant data for elevations of some military installations. Could it be that South Coronado Island (Mexican territory) simply hasn't been fully surveyed due to its inaccessibility? The height of the island summits are necessary for navigation, so I'd like to think you can trust the nautical chart. So if that beacon on the north summit is 672', the south peak is about 15% taller based on pixel comparisons of some lateral views of the island from Tijuana, which puts it right around 770'. 

Is that wishful thinking? Did I just manipulate that estimate so that it could coincidentally be at eye level from my viewspot on Mount Soledad, 30+ miles away?

Suppose Google Earth is correct, and that peak is 488' in elevation? Assuming that, can +282' above that at that distance to 770' eye level be estimated? 

The distance is 30.5 miles. On a globe with standard atmosphere, there would be a drop of 532' away from eye level. Roughly (very roughly), the island should appear below level eye sight by an amount about equal to its full height if we're assuming Google Earth is more correct than nautical charts.

Sound okay?

Anyone? Anyone? Bueller?
« Last Edit: January 02, 2019, 05:26:09 PM by Bobby Shafto »

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Offline Bobby Shafto

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More than 1x the height of the island?


  • Either the island summit is higher than even the highest figure, or
  • the curve of the earth was less flattened than standard atmospheric condition, or
  • Something was off with the water level alignment, or
  • ?

Camera-to-Water Level distance: ~65 feet


Camera location: 32.839105, -117.245358


Level location: about 32.838927, -117.245342
« Last Edit: January 02, 2019, 10:55:46 PM by Bobby Shafto »

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Offline Bobby Shafto

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Visibility is as clear as it gets here. I'm seeing snow-capped San Antonio, San Gorgonio and San Jacinto mountain summits to the N and NE. I don't think that horizon is ever going to appear any higher; it's certainly never going to appear above the summit of South Coronado island, which is below eye level from this vantage point on Mt Soledad.



Absent any contrary argument or objection, I'll consider this zetetic project closed.

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Offline Tom Bishop

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More than 1x the height of the island?

Is your argument that eye level is way up there where the water lines up and that the sea horizon is the imperceptible drop of the globe?

This picture seems, to me, to be evidence of what Rowbotham said:

http://www.sacred-texts.com/earth/za/za32.htm

Quote
The error in perspective, which is almost universally committed, consists in causing lines dissimilarly distant from the eye-line to converge to one and the same vanishing point. Whereas it is demonstrable that lines most distant from an eye-line must of necessity converge less rapidly, and must be carried further over the eye-line before they meet it at the angle one minute, which constitutes the vanishing point.

...

The theory which affirms that all parallel lines converge to one and the same point on the eye-line, is an error. It is true only of lines equi-distant from the eye-line; lines more or less apart meet the eye-line at different distances, and the point at which they meet is that only where each forms the angle of one minute of a degree, or such other angular measure as may be decided upon as the vanishing point. This is the true law of perspective as shown by nature herself; any idea to the contrary is fallacious, and will deceive whoever may hold and apply it to practice.
« Last Edit: January 04, 2019, 05:01:49 AM by Tom Bishop »

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Offline Bobby Shafto

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Is your argument...

...that not only does the horizon not always rise to eye level, but distant points that are at the same height don't rise to eye level.


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Offline Tom Bishop

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Is your argument...

...that not only does the horizon not always rise to eye level, but distant points that are at the same height don't rise to eye level.



The globe horizon should be barely under the Flat Earth horizon. There is clearly something wrong if you are getting that result.
« Last Edit: January 04, 2019, 06:11:27 AM by Tom Bishop »

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Offline Bobby Shafto

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The globe horizon should be barely under the Flat Earth horizon. There is clearly something wrong if you are getting that result.
"Barely" as in about half a degree?