[ScaryGary]

Wondering if anyone has tested these questions and can provide an answer?

1) With high powered optics, if watching the sunset on a flat surface such as ocean (we know water is flat because it levels out), should the sun set occur later relative to a person's perception of sunset with no optics?  Would the difference be noticeable?  Not sure how far the highest powered optics can view

2) How far out in the ocean with high powered optics should we be able to see based on heliocentric earth view - Given the earth's curvature recesses 8 inches every mile?

[3DGeek]

Wondering if anyone has tested these questions and can provide an answer?

1) With high powered optics, if watching the sunset on a flat surface such as ocean (we know water is flat because it levels out), should the sun set occur later relative to a person's perception of sunset with no optics?  Would the difference be noticeable?  Not sure how far the highest powered optics can view

2) How far out in the ocean with high powered optics should we be able to see based on heliocentric earth view - Given the earth's curvature recesses 8 inches every mile?

Important correction:

* The rule isn't '8 inches every mile' - it's '8 inches every mile SQUARED' - so at one mile, it's 8"x1 at two miles it's 8"x4, at three miles it's 8"x9 and so forth.
* But the rule isn't correct - it's only an approximation...so don't use it beyond a few tens of miles.  8" per mile-squared describes a parabola - not a sphere.

Many people misunderstand the rule - and say it the way you did - and many others push it beyond where it's a reasonable approximation...both things are serious errors that can derail logical thought!

[ScaryGary]

Thanks for clarification, 3DGeek, but I am still looking for answers.

[mtnman]

In addition to 3D's comment about parabola vs sphere, there is also another thing to watch for. The formula to calculate horizon and the amount hidden of distant objects also has an input for viewing height. Most people just quoting the 8 inches/mile don't realize that by just looking at that part of the formula they are effectively making the viewing height zero, which is probably never really the case.

If you are standing at the edge of the ocean with your feet in the water, your eyes are still several feet above the water. It doesn't sound like much, but it makes a difference.

Checkout this page for a calculator using open source code https://dizzib.github.io/earth/curve-calc

[ScaryGary]

In addition to 3D's comment about parabola vs sphere, there is also another thing to watch for. The formula to calculate horizon and the amount hidden of distant objects also has an input for viewing height. Most people just quoting the 8 inches/mile don't realize that by just looking at that part of the formula they are effectively making the viewing height zero, which is probably never really the case.

If you are standing at the edge of the ocean with your feet in the water, your eyes are still several feet above the water. It doesn't sound like much, but it makes a difference.

Checkout this page for a calculator using open source code https://dizzib.github.io/earth/curve-calc

This answer did nothing for me.  Looking for answers not lectures...thanks

[Uetzicle]

The answer is, as long as the telescope is at the same height as your eyes, the horizon won't change, and what is visible won't change. It will just appear larger.

So, if your eyes are 6 feet above the surface, and the telescope has a mount that is 6 feet tall, the horizon on the ocean will be exactly the same, almost exactly 3 miles away (2.999547 miles, using the calculator mtmman linked to). You will see the same thing with both, it will just be magnified with the telescope.

So, for #1, the sun will set at the exact same time, bare eyes or telescope (and don't look at the sun with a telescope without filters).

And #2, how far out? With your eyes and the telescope both at 6 feet, 3 miles.

For there to actually be a change to these two things, elevate yourself. Or shrink yourself. Stand on a ladder, or on the 2nd floor of a building, and the sun will set ever so slightly later. And you'll be able to see a mile or two further away.

If you want a really good test of this, wait a few months and go to a large frozen lake in northern Minnesota. There are plenty of them larger than 3 miles across. You won't have waves to 'obstruct the view'. Just a flat sheet of ice (all but for the curvature of the earth, of course! ;-)

[ScaryGary]

The answer is, as long as the telescope is at the same height as your eyes, the horizon won't change, and what is visible won't change. It will just appear larger.

So, if your eyes are 6 feet above the surface, and the telescope has a mount that is 6 feet tall, the horizon on the ocean will be exactly the same, almost exactly 3 miles away (2.999547 miles, using the calculator mtmman linked to). You will see the same thing with both, it will just be magnified with the telescope.

So, for #1, the sun will set at the exact same time, bare eyes or telescope (and don't look at the sun with a telescope without filters).

And #2, how far out? With your eyes and the telescope both at 6 feet, 3 miles.

For there to actually be a change to these two things, elevate yourself. Or shrink yourself. Stand on a ladder, or on the 2nd floor of a building, and the sun will set ever so slightly later. And you'll be able to see a mile or two further away.

If you want a really good test of this, wait a few months and go to a large frozen lake in northern Minnesota. There are plenty of them larger than 3 miles across. You won't have waves to 'obstruct the view'. Just a flat sheet of ice (all but for the curvature of the earth, of course! ;-)

Good answer, thank you.  I guess the horizon occurs because things are shrinking as they get further away.  This is most noticeable with equal height telephone poles which appear to get smaller and smaller.  Also kinda strange how the clouds basically touch the ocean where the horizon occurs whereas they are easily 100s of feet above us when directly overhead.

[douglips]

Were you asking for a Round Earth theory of the horizon, or a Flat Earth theory of the horizon?

The round earth theory of the horizon is that when the earth curves away from you you can no longer see things on the earth, that's where the 8 inches/mile^2 rule of thumb comes in. In this model, the horizon is about 3 miles away if you are six feet tall standing on the beach at sea level. An object that is beyond that distance will only be partially visible, depending on atmospheric conditions.

I think, if I understand Tom Bishop, that the flat earth theory of the horizon is that there is a certain distance beyond which all objects tend to zero apparent size. I don't have information on what that distance is, but it appears that the distance from an observer to the sun at sunset (3000 miles up, 6000 miles away in one interpretation of FET, or about 6700 miles away).

[mtnman]

Were you asking for a Round Earth theory of the horizon, or a Flat Earth theory of the horizon?

The round earth theory of the horizon is that when the earth curves away from you you can no longer see things on the earth, that's where the 8 inches/mile^2 rule of thumb comes in. In this model, the horizon is about 3 miles away if you are six feet tall standing on the beach at sea level. An object that is beyond that distance will only be partially visible, depending on atmospheric conditions.

I think, if I understand Tom Bishop, that the flat earth theory of the horizon is that there is a certain distance beyond which all objects tend to zero apparent size. I don't have information on what that distance is, but it appears that the distance from an observer to the sun at sunset (3000 miles up, 6000 miles away in one interpretation of FET, or about 6700 miles away).

FYI, Tom also states that the vanishing point at sunset is caused by things blocking the direct view (trees, waves, etc.) which indicates to me that there should be no sunset visible from high altitude, like from an airplane or a mountain top. I pressed this question in a thread recently, but never got an answer.

If FE defines a horizon as a finite distance past which objects can not be seen, then how do we see planets, stars and galaxies in the night sky?

[Tom Bishop]

Were you asking for a Round Earth theory of the horizon, or a Flat Earth theory of the horizon?

The round earth theory of the horizon is that when the earth curves away from you you can no longer see things on the earth, that's where the 8 inches/mile^2 rule of thumb comes in. In this model, the horizon is about 3 miles away if you are six feet tall standing on the beach at sea level. An object that is beyond that distance will only be partially visible, depending on atmospheric conditions.

I think, if I understand Tom Bishop, that the flat earth theory of the horizon is that there is a certain distance beyond which all objects tend to zero apparent size. I don't have information on what that distance is, but it appears that the distance from an observer to the sun at sunset (3000 miles up, 6000 miles away in one interpretation of FET, or about 6700 miles away).

FYI, Tom also states that the vanishing point at sunset is caused by things blocking the direct view (trees, waves, etc.) which indicates to me that there should be no sunset visible from high altitude, like from an airplane or a mountain top. I pressed this question in a thread recently, but never got an answer.

If FE defines a horizon as a finite distance past which objects can not be seen, then how do we see planets, stars and galaxies in the night sky?

The perspective lines intersect each other at a finite distance. This does not mean that all light disappears at that finite point where they intersect. It is mainly the angles of where the body is positioned that is affected.

In the case of the sun at sunset, the explanation is that the perspective lines are perfect, but the surface of the earth is not perfect, and there will be an area upon which something can disappear behind. Where the perspective lines merge in the distance the photons from that area are increasingly trying to occupy the same space at once. Some of these photons are blocked out since the earth is not perfectly or mathematically flat and there are slight imperfections on the surface, as the perfect lines merge into the non-perfect earth.

It is mentioned in Earth Not a Globe, in fact, that the sunset takes longer when the seas are calm compared to when they are more disturbed.

When the stars and planets are above your head they are not affected by ground imperfections, and so there is nothing blocking the light.

[mtnman]

FYI, Tom also states that the vanishing point at sunset is caused by things blocking the direct view (trees, waves, etc.) which indicates to me that there should be no sunset visible from high altitude, like from an airplane or a mountain top. I pressed this question in a thread recently, but never got an answer.

If FE defines a horizon as a finite distance past which objects can not be seen, then how do we see planets, stars and galaxies in the night sky?

The perspective lines intersect each other at a finite distance. This does not mean that all light disappears at that finite point where they intersect. It is mainly the angles of where the body is positioned that is affected.

In the case of the sun at sunset, the explanation is that the perspective lines are perfect, but the surface of the earth is not perfect, and there will be an area upon which something can disappear behind. Where the perspective lines merge in the distance the photons from that area are increasingly trying to occupy the same space at once. Some of these photons are blocked out since the earth is not perfectly or mathematically flat and there are slight imperfections on the surface, as the perfect lines merge into the non-perfect earth.

It is mentioned in Earth Not a Globe, in fact, that the sunset takes longer when the seas are calm compared to when they are more disturbed.

When the stars and planets are above your head they are not affected by ground imperfections, and so there is nothing blocking the light.

Forget about the imperfect surface of the Earth for a moment. How would a sunset occur when viewed from an aircraft a few thousand feet in the air? There are no Earth imperfections, mountains, waves, or other things to block the view.

[Tom Bishop]

FYI, Tom also states that the vanishing point at sunset is caused by things blocking the direct view (trees, waves, etc.) which indicates to me that there should be no sunset visible from high altitude, like from an airplane or a mountain top. I pressed this question in a thread recently, but never got an answer.

If FE defines a horizon as a finite distance past which objects can not be seen, then how do we see planets, stars and galaxies in the night sky?

The perspective lines intersect each other at a finite distance. This does not mean that all light disappears at that finite point where they intersect. It is mainly the angles of where the body is positioned that is affected.

In the case of the sun at sunset, the explanation is that the perspective lines are perfect, but the surface of the earth is not perfect, and there will be an area upon which something can disappear behind. Where the perspective lines merge in the distance the photons from that area are increasingly trying to occupy the same space at once. Some of these photons are blocked out since the earth is not perfectly or mathematically flat and there are slight imperfections on the surface, as the perfect lines merge into the non-perfect earth.

It is mentioned in Earth Not a Globe, in fact, that the sunset takes longer when the seas are calm compared to when they are more disturbed.

When the stars and planets are above your head they are not affected by ground imperfections, and so there is nothing blocking the light.

Forget about the imperfect surface of the Earth for a moment. How would a sunset occur when viewed from an aircraft a few thousand feet in the air? There are no Earth imperfections, mountains, waves, or other things to block the view.

The horizon is always at eye level with the observer, even on an airplane.

[xenotolerance]

No, it isn't.

[Curious Squirrel]

No, it isn't.

It is because they need it to be, and Rowbotham has declared theodolites (? the thing to measure the dip angle) inaccurate in ENaG. If someone can dig up the actual quote that would be swell, but essentially: "I looked through his instrument and saw a drop. Upon removing the glass from the instrument I could no longer see a drop. Therefore the instrument is in error/the glass creates an error." I unfortunately don't recall the chapter right now. Maybe I'll dig it up later when I'm back from vacation.

[Tom Bishop]

No, it isn't.

It is because they need it to be, and Rowbotham has declared theodolites (? the thing to measure the dip angle) inaccurate in ENaG. If someone can dig up the actual quote that would be swell, but essentially: "I looked through his instrument and saw a drop. Upon removing the glass from the instrument I could no longer see a drop. Therefore the instrument is in error/the glass creates an error." I unfortunately don't recall the chapter right now. Maybe I'll dig it up later when I'm back from vacation.

Rowbotham is correct about that device. Look up Snell's Law.

[xenotolerance]

Theodolites, Snell's law.

Theodolites are legit, Rowbotham was a hack who did not understand refraction.

[inquisitive]

No, it isn't.

It is because they need it to be, and Rowbotham has declared theodolites (? the thing to measure the dip angle) inaccurate in ENaG. If someone can dig up the actual quote that would be swell, but essentially: "I looked through his instrument and saw a drop. Upon removing the glass from the instrument I could no longer see a drop. Therefore the instrument is in error/the glass creates an error." I unfortunately don't recall the chapter right now. Maybe I'll dig it up later when I'm back from vacation.

Rowbotham is correct about that device. Look up Snell's Law.

Please provide a link to documentation on theodolites to prove your statement.

[Uetzicle]

Okay...theodolites are out. So just use a straw, protractor, and a weighted string. No optics, no 'scary deceitful technology', just a hole to look through and a string to show the angle. Not as precise, but it will still show you the angles to the horizon change with elevation.

But to the whole 'horizon is always at eye level' thing. It is surely a biological, subconscious response to automatically orient your vision on the horizon, or what you perceive as the horizon. Sort of an evolutionary behavior of a species that learned to walk upright and look in front of themselves with binocular vision. "There's the line that helps my eyes tell my feet which way is forward. So put it in the middle of my vision." (there's probably already a name for it...my biology knowledge is limited)

So whether you realize it or not, your eyes will adjust the angle of vision automatically. 'Straight ahead' usually just means 'angled down to the horizon'.

Or as somebody much wiser once said, "Your eyes can deceive you. Don't trust them."

[Uetzicle]

Okay...theodolites are out. So just use a straw, protractor, and a weighted string. No optics, no 'scary deceitful technology', just a hole to look through and a string to show the angle. Not as precise, but it will still show you the angles to the horizon change with elevation.

But to the whole 'horizon is always at eye level' thing. It is surely a biological, subconscious response to automatically orient your vision on the horizon, or what you perceive as the horizon. Sort of an evolutionary behavior of a species that learned to walk upright and look in front of themselves with binocular vision. "There's the line that helps my eyes tell my feet which way is forward. So put it in the middle of my vision." (there's probably already a name for it...my biology knowledge is limited)

So whether you realize it or not, your eyes will adjust the angle of vision automatically. 'Straight ahead' usually just means 'angled down to the horizon'.

Or as somebody much wiser once said, "Your eyes can deceive you. Don't trust them."

Here it is. 'Gaze Stabilization or Biological Image Stabilization. Excellent read. http://www.sciencedirect.com/science/article/pii/S0960982216310041

[ScaryGary]

No, it isn't.

Just another programmed sheep believing everything they are told but not the truth itself.