What altitude do you have to be at before the curvature of the EarthSo
becomes discernible to the naked eye?
My answer, if the surface around you is sufficiently flat all the way
to the horizon (e.g. on the sea) is ?any nonzero altitude will do?.
if you?re standing on the deck of even a small boat, the curvature of
the horizon is already discernible.
Because, think about it: what shape is the horizon? A flat horizontal
line? No, it?s a circle that goes all the way around you. A circle is
a curve. QED.
On the other hand, many pictures taken at high altitudes, purporting
to show the curve of the horizon, are in fact misleading, because a
lot of the curvature you see is distortion from using a wide-angle
lens.
On Fri, 3 Apr 2026 03:38:28 -0000 (UTC), Lawrence D?Oliveiro
<ldo@nz.invalid> wrote:
What altitude do you have to be at before the curvature of the Earth >>becomes discernible to the naked eye?
My answer, if the surface around you is sufficiently flat all the way to >>the horizon (e.g. on the sea) is ?any nonzero altitude will do?. So if >>you?re standing on the deck of even a small boat, the curvature of the >>horizon is already discernible.
Because, think about it: what shape is the horizon? A flat horizontal
line? No, it?s a circle that goes all the way around you. A circle is a >>curve. QED.
On the other hand, many pictures taken at high altitudes, purporting to >>show the curve of the horizon, are in fact misleading, because a lot of
the curvature you see is distortion from using a wide-angle lens.
Actually, IIRC, man's first clue that the Earth was rounded was when
sailors got far enough out to see mountains slowly rising from the
horizon as they got closer. Or maybe Bedu on camels coming out of the
desert watching the walls of the town they were going to slowly rise
from the sand.
This sort of thing wouldn't happen if the Earth were flat.
What altitude do you have to be at before the curvature of the Earth
becomes discernible to the naked eye?
My answer, if the surface around you is sufficiently flat all the way
to the horizon (e.g. on the sea) is ?any nonzero altitude will do?. So
if you?re standing on the deck of even a small boat, the curvature of
the horizon is already discernible.
Because, think about it: what shape is the horizon? A flat horizontal
line? No, it?s a circle that goes all the way around you. A circle is
a curve. QED.
On the other hand, many pictures taken at high altitudes, purporting
to show the curve of the horizon, are in fact misleading, because a
lot of the curvature you see is distortion from using a wide-angle
lens.
On Fri, 03 Apr 2026 08:57:48 -0700, Paul S Person wrote:to
On Fri, 3 Apr 2026 03:38:28 -0000 (UTC), Lawrence D?Oliveiro
<ldo@nz.invalid> wrote:
What altitude do you have to be at before the curvature of the Earth >>>becomes discernible to the naked eye?
My answer, if the surface around you is sufficiently flat all the way
athe horizon (e.g. on the sea) is ?any nonzero altitude will do?. So if >>>you?re standing on the deck of even a small boat, the curvature of the >>>horizon is already discernible.
Because, think about it: what shape is the horizon? A flat horizontal >>>line? No, it?s a circle that goes all the way around you. A circle is
tocurve. QED.
On the other hand, many pictures taken at high altitudes, purporting
ofshow the curve of the horizon, are in fact misleading, because a lot
the curvature you see is distortion from using a wide-angle lens.
Actually, IIRC, man's first clue that the Earth was rounded was when
sailors got far enough out to see mountains slowly rising from the
horizon as they got closer. Or maybe Bedu on camels coming out of the
desert watching the walls of the town they were going to slowly rise
from the sand.
This sort of thing wouldn't happen if the Earth were flat.
And there's always Wendover, Utah.
What altitude do you have to be at before the curvature of the Earth
becomes discernible to the naked eye?
My answer, if the surface around you is sufficiently flat all the way
to the horizon (e.g. on the sea) is ?any nonzero altitude will do?. So
if you?re standing on the deck of even a small boat, the curvature of
the horizon is already discernible.
Because, think about it: what shape is the horizon? A flat horizontal
line? No, it?s a circle that goes all the way around you. A circle is
a curve. QED.
On the other hand, many pictures taken at high altitudes, purporting
to show the curve of the horizon, are in fact misleading, because a
lot of the curvature you see is distortion from using a wide-angle
lens.
On Fri, 3 Apr 2026 03:38:28 -0000 (UTC), Lawrence D?Oliveiro
<ldo@nz.invalid> wrote:
What altitude do you have to be at before the curvature of the Earth
becomes discernible to the naked eye?
My answer, if the surface around you is sufficiently flat all the way
to the horizon (e.g. on the sea) is ?any nonzero altitude will do?. So
if you?re standing on the deck of even a small boat, the curvature of
the horizon is already discernible.
Because, think about it: what shape is the horizon? A flat horizontal
line? No, it?s a circle that goes all the way around you. A circle is
a curve. QED.
On the other hand, many pictures taken at high altitudes, purporting
to show the curve of the horizon, are in fact misleading, because a
lot of the curvature you see is distortion from using a wide-angle
lens.
Actually, IIRC, man's first clue that the Earth was rounded was when
sailors got far enough out to see mountains slowly rising from the
horizon as they got closer. Or maybe Bedu on camels coming out of the
desert watching the walls of the town they were going to slowly rise
from the sand.
This sort of thing wouldn't happen if the Earth were flat.A
On 4/3/2026 11:57 AM, Paul S Person wrote:do?. So
On Fri, 3 Apr 2026 03:38:28 -0000 (UTC), Lawrence D?Oliveiro
<ldo@nz.invalid> wrote:
What altitude do you have to be at before the curvature of the Earth
becomes discernible to the naked eye?
My answer, if the surface around you is sufficiently flat all the way
to the horizon (e.g. on the sea) is ?any nonzero altitude will
ofif you?re standing on the deck of even a small boat, the curvature
isthe horizon is already discernible.
Because, think about it: what shape is the horizon? A flat horizontal
line? No, it?s a circle that goes all the way around you. A circle
a curve. QED.
On the other hand, many pictures taken at high altitudes, purporting
to show the curve of the horizon, are in fact misleading, because a
lot of the curvature you see is distortion from using a wide-angle
lens.
Actually, IIRC, man's first clue that the Earth was rounded was when
sailors got far enough out to see mountains slowly rising from the
horizon as they got closer. Or maybe Bedu on camels coming out of the
desert watching the walls of the town they were going to slowly rise
from the sand.
This sort of thing wouldn't happen if the Earth were flat.A
Also, changes in which stars stayed above the horizon all night
as one moved north or south.
On 4/2/2026 11:38 PM, Lawrence D?Oliveiro wrote:do?. So
What altitude do you have to be at before the curvature of the Earth
becomes discernible to the naked eye?
My answer, if the surface around you is sufficiently flat all the way
to the horizon (e.g. on the sea) is ?any nonzero altitude will
ofif you?re standing on the deck of even a small boat, the curvature
isthe horizon is already discernible.
Because, think about it: what shape is the horizon? A flat horizontal
line? No, it?s a circle that goes all the way around you. A circle
a curve. QED.
On the other hand, many pictures taken at high altitudes, purporting
to show the curve of the horizon, are in fact misleading, because a
lot of the curvature you see is distortion from using a wide-angle
lens.
Greek philosphers were discussing the the spherical shape of the Earth
in the 5th century BC, and Eratosthenes calculated the circumference
to under 3% error in the 3rd century BC.
On Sat, 4 Apr 2026 18:11:21 -0400, Cryptoengineer
<petertrei@gmail.com> wrote:
On 4/2/2026 11:38 PM, Lawrence D?Oliveiro wrote:
What altitude do you have to be at before the curvature of the Earth becomes discernible to the naked eye?
My answer, if the surface around you is sufficiently flat all the way
to the horizon (e.g. on the sea) is ?any nonzero altitude will do?. So
if you?re standing on the deck of even a small boat, the curvature of
the horizon is already discernible.
Because, think about it: what shape is the horizon? A flat horizontal line? No, it?s a circle that goes all the way around you. A circle is
a curve. QED.
On the other hand, many pictures taken at high altitudes, purporting
to show the curve of the horizon, are in fact misleading, because a
lot of the curvature you see is distortion from using a wide-angle
lens.
Greek philosphers were discussing the the spherical shape of the Earth
in the 5th century BC, and Eratosthenes calculated the circumference
to under 3% error in the 3rd century BC.
Oh, yeah, that the Earth is round has been known to the intelligentsia
for a long, long time. Hoi polloi still contains elements who think it
is flat.
On Apr 5, 2026, Paul S Person wroteEarth
(in article<6b05tk5nmq14qemm43bjvfqrcqft899voi@4ax.com>):
On Sat, 4 Apr 2026 18:11:21 -0400, Cryptoengineer
<petertrei@gmail.com> wrote:
On 4/2/2026 11:38 PM, Lawrence D?Oliveiro wrote:
What altitude do you have to be at before the curvature of the
waybecomes discernible to the naked eye?
My answer, if the surface around you is sufficiently flat all the
do?. Soto the horizon (e.g. on the sea) is ?any nonzero altitude will
curvature ofif you?re standing on the deck of even a small boat, the
horizontalthe horizon is already discernible.
Because, think about it: what shape is the horizon? A flat
circle isline? No, it?s a circle that goes all the way around you. A
purportinga curve. QED.
On the other hand, many pictures taken at high altitudes,
ato show the curve of the horizon, are in fact misleading, because
Earthlot of the curvature you see is distortion from using a wide-angle
lens.
Greek philosphers were discussing the the spherical shape of the
to bein the 5th century BC, and Eratosthenes calculated the circumference
to under 3% error in the 3rd century BC.
Oh, yeah, that the Earth is round has been known to the intelligentsia
for a long, long time. Hoi polloi still contains elements who think it
is flat.
Mostly for religious reasons. Flat Earthers in Christian territory tend
closely related to creationists. According to them, the Bible must betaken
literally, and as the Bible mentions ?four corners? and has Yeshuago
high enough that he can see all of the Earth at the same time, plus ofcourse
the ?firmament? above anf ?the waters? below (that?s where theFood
waters came from, and where they returned...) those who say that theEarth
isn?t flat are all godless atheists who are doomed, doomed, DOOMEDthey
say. For some reason the flearther who told me this got offended when I >started laughing.
Further info on flearthers is available at Quora and at Reddit.
[...] sailors far enough out to
notice the effect had to wait until they felt willing to sail out of
sight of the land.
Further info on flearthers is available at Quora and at Reddit.
Paul S Person wrote:
[...] sailors far enough out to
notice the effect had to wait until they felt willing to sail out of
sight of the land.
But... how do they know they are out of sight of land? They have to
sail away of it until part of it is hidden. Or until they still can
see something from masttop that's no longer visible from deck.
On Fri, 03 Apr 2026 08:57:48 -0700, Paul S Person wrote:Could you follow up on that a bit. I've been to Wendover and didn't
On Fri, 3 Apr 2026 03:38:28 -0000 (UTC), Lawrence D?Oliveiro
<ldo@nz.invalid> wrote:
What altitude do you have to be at before the curvature of the Earth
becomes discernible to the naked eye?
My answer, if the surface around you is sufficiently flat all the way to >>> the horizon (e.g. on the sea) is ?any nonzero altitude will do?. So if
you?re standing on the deck of even a small boat, the curvature of the
horizon is already discernible.
Because, think about it: what shape is the horizon? A flat horizontal
line? No, it?s a circle that goes all the way around you. A circle is a
curve. QED.
On the other hand, many pictures taken at high altitudes, purporting to
show the curve of the horizon, are in fact misleading, because a lot of
the curvature you see is distortion from using a wide-angle lens.
Actually, IIRC, man's first clue that the Earth was rounded was when
sailors got far enough out to see mountains slowly rising from the
horizon as they got closer. Or maybe Bedu on camels coming out of the
desert watching the walls of the town they were going to slowly rise
from the sand.
This sort of thing wouldn't happen if the Earth were flat.
And there's always Wendover, Utah.
WolfFan wrote:
Further info on flearthers is available at Quora and at Reddit.
The Flat Earth Society has members all over the globe.
-is
On 4/4/26 00:25, Charles Packer wrote:curvature
On Fri, 03 Apr 2026 08:57:48 -0700, Paul S Person wrote:
On Fri, 3 Apr 2026 03:38:28 -0000 (UTC), Lawrence D?Oliveiro
<ldo@nz.invalid> wrote:
What altitude do you have to be at before the curvature of the Earth
becomes discernible to the naked eye?
My answer, if the surface around you is sufficiently flat all the way
to the horizon (e.g. on the sea) is ?any nonzero altitude will do?.
So if you?re standing on the deck of even a small boat, the
isof the horizon is already discernible.
Because, think about it: what shape is the horizon? A flat horizontal
line? No, it?s a circle that goes all the way around you. A circle
Could you follow up on that a bit. I've been to Wendover and didn'ta curve. QED.
On the other hand, many pictures taken at high altitudes, purporting
to show the curve of the horizon, are in fact misleading, because a
lot of the curvature you see is distortion from using a wide-angle
lens.
Actually, IIRC, man's first clue that the Earth was rounded was when
sailors got far enough out to see mountains slowly rising from the
horizon as they got closer. Or maybe Bedu on camels coming out of the
desert watching the walls of the town they were going to slowly rise
from the sand.
This sort of thing wouldn't happen if the Earth were flat.
And there's always Wendover, Utah.
notice any roundness. Of course, I wasn't looking for it. And there was
too much heat distortion over the salt flats to get a good view of far
off.
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