Reply
 
Thread Tools Display Modes
  #1  
Old 10-15-2018, 07:50 AM
bizerta bizerta is offline
Guest
 
Join Date: Dec 1999
Location: wilmington, ma
Posts: 862
How can one prove that the earth is a sphere (or close to it)?

Yesterday, on CBS Sunday Morning, they had a segment on flat-earthers. Are these people just ignorant or are they putting us on?

I was once on a cruise ship at sea on a pristine cloudless evening. As I stood on the deck, I watched the sun disappear below the horizon. As soon as the sun vanished, I ran up a flight to the next deck and witnessed the sun setting again about 10 seconds later.

What are some other simple ways we, as common folk, can demonstrate that the earth is round?
  #2  
Old 10-15-2018, 07:53 AM
running coach's Avatar
running coach running coach is offline
Arms of Steel, Leg of Jello
Charter Member
 
Join Date: Nov 2000
Location: Riding my handcycle
Posts: 35,456
The fact that no one has ever come to an edge.
  #3  
Old 10-15-2018, 07:57 AM
pulykamell pulykamell is online now
Charter Member
 
Join Date: May 2000
Location: SW Side, Chicago
Posts: 45,337
Quote:
Originally Posted by running coach View Post
The fact that no one has ever come to an edge.
To paraphrase Scott Kelly on Wait Wait Don't Tell Me, if there were an edge don't you think that'd be a cool place to visit?
  #4  
Old 10-15-2018, 07:58 AM
mcgato mcgato is offline
Guest
 
Join Date: Aug 2010
Location: Hoboken
Posts: 1,288
The circumference of the earth was estimated in about 240 BC by Eratosthenes. That pretty much implies that the earth is spheroid.
  #5  
Old 10-15-2018, 08:01 AM
Alpha Twit's Avatar
Alpha Twit Alpha Twit is offline
Guest
 
Join Date: Jun 2009
Location: Somewhere south of normal
Posts: 1,634
Lunar eclipses

As the Earth passes between the Sun and Moon, it always produces a circular shadow. It's not possible for a flat, disk like Earth to always produce such a shadow. Only a nearly spherical world can do that.

Quote:
Originally Posted by bizerta View Post
Are these people just ignorant or are they putting us on?
I don't see these conditions as being mutually exclusive.
__________________
Somebody load the manatee cannon!

Last edited by Alpha Twit; 10-15-2018 at 08:03 AM.
  #6  
Old 10-15-2018, 08:16 AM
bizerta bizerta is offline
Guest
 
Join Date: Dec 1999
Location: wilmington, ma
Posts: 862
Quote:
Originally Posted by Alpha Twit View Post
Lunar eclipses

As the Earth passes between the Sun and Moon, it always produces a circular shadow. It's not possible for a flat, disk like Earth to always produce such a shadow. Only a nearly spherical world can do that.
OP here. I like this proof.

On the CBS segment, one flat-earther had a model where both the sun and moon were above the horizon and ran in a circle above the earth. After all, both the sun and the moon are each visible somewhere at any point in time. So, if the sun and moon were both above the flat earth, what is casting a shadow on the moon?
  #7  
Old 10-15-2018, 08:39 AM
Alpha Twit's Avatar
Alpha Twit Alpha Twit is offline
Guest
 
Join Date: Jun 2009
Location: Somewhere south of normal
Posts: 1,634
Quote:
Originally Posted by bizerta View Post
OP here. I like this proof.
Watch this video from Neil deGrasse Tyson.

I consider NDT to be a pompous ass but he communicates complex science issues well and he can be a most useful mammal.
__________________
Somebody load the manatee cannon!
  #8  
Old 10-15-2018, 08:58 AM
Munch Munch is offline
Guest
 
Join Date: Mar 2000
Location: Parts Unknown
Posts: 22,129
Quote:
Originally Posted by bizerta View Post
OP here. I like this proof.

On the CBS segment, one flat-earther had a model where both the sun and moon were above the horizon and ran in a circle above the earth. After all, both the sun and the moon are each visible somewhere at any point in time. So, if the sun and moon were both above the flat earth, what is casting a shadow on the moon?
They deny this proof by saying that the moon is self-illuminating, and that lunar eclipses are the moon cycling through something. It's irrefutable in its pure lunacy. Those are the arguments that I think are good at just being able to point at the flat earth movement and hold them up as crackpots.

What I find to be a solid argument is time lapse photos of the stars from the northern hemisphere, the equator, and the southern hemisphere, side-by-side-by-side.

Last edited by Munch; 10-15-2018 at 08:59 AM.
  #9  
Old 10-15-2018, 09:08 AM
ftg's Avatar
ftg ftg is offline
Guest
 
Join Date: Feb 2001
Location: Not the PNW :-(
Posts: 17,875
Quote:
Originally Posted by Alpha Twit View Post
Lunar eclipses

As the Earth passes between the Sun and Moon, it always produces a circular shadow. It's not possible for a flat, disk like Earth to always produce such a shadow. Only a nearly spherical world can do that.
Good news and bad news.

The bad news: A lot of shapes other that spheres produce circular shadows from every angle. Meissner Bodies (relatives of the Reuleaux triangle), for example.

The good news: These are more complicated than spheres, would require quite extraordinary Physics to explain why the Earth has that shape, etc.

A lot of simple things can show deep problems with Flat Earth nonsense. E.g., why can't people in the N. Hemisphere see stuff at the celestial S. pole and vice versa. Call someone on the opposite side of the Earth and ask them what time of day it is. And on and on.

Of course a few Flat Earthers come up with Magical "Physics" to explain this and a million other things. But outside of simple drawings and such they have no real Math, Physics, experiments, data, etc. to back them up.
  #10  
Old 10-15-2018, 09:41 AM
Novelty Bobble Novelty Bobble is offline
Member
 
Join Date: Nov 2009
Location: South East England
Posts: 7,903
Quote:
Originally Posted by mcgato View Post
The circumference of the earth was estimated in about 240 BC by Eratosthenes. That pretty much implies that the earth is spheroid.
I was going to post exactly the same point. The beauty of it being that it is something that can be easily replicated by any suitably motivated flat-earth nutjob.

You need two groups of people, some sticks and string if you are feeling technical and the ability to roughly measure distance and manipulate angles by means of simple formula.

It is one the great experiments of that, or any age.
  #11  
Old 10-15-2018, 09:43 AM
Bullitt's Avatar
Bullitt Bullitt is online now
Member
 
Join Date: Apr 2012
Location: SF Giants Nation 10-12-14
Posts: 24,262
Quote:
Originally Posted by running coach View Post
The fact that no one has ever come to an edge.
Thatís not a definitive proof.
  #12  
Old 10-15-2018, 10:02 AM
Bullitt's Avatar
Bullitt Bullitt is online now
Member
 
Join Date: Apr 2012
Location: SF Giants Nation 10-12-14
Posts: 24,262
Quote:
Originally Posted by Alpha Twit View Post
Lunar eclipses

As the Earth passes between the Sun and Moon, it always produces a circular shadow. It's not possible for a flat, disk like Earth to always produce such a shadow. Only a nearly spherical world can do that.
I like this proof too, but I wonder how the Flat Earthers argue against it.

About the recent solar eclipse, on the wiki page for Modern flat Earth societies,
Quote:
The solar eclipse of 21 August 2017 gave rise to numerous YouTube videos purporting to show how the details of the eclipse prove the Earth is flat.
  #13  
Old 10-15-2018, 10:17 AM
Chronos's Avatar
Chronos Chronos is online now
Charter Member
Moderator
 
Join Date: Jan 2000
Location: The Land of Cleves
Posts: 79,433
ftg, those shapes don't cast circular shadows. Here's a picture of some.

Bullitt, want to lay odds that the argument, in full, consists of "the details of the eclipse prove that the Earth is flat!", with no actual calculations?
  #14  
Old 10-15-2018, 10:17 AM
Voyager's Avatar
Voyager Voyager is offline
Charter Member
 
Join Date: Aug 2002
Location: Deep Space
Posts: 44,193
Quote:
Originally Posted by Bullitt View Post
Thatís not a definitive proof.
In this case it is since we've circumnavigated the Earth both East-West and North-South, so we've exhausted the search space. We can't prove that there isn't a hole through the Earth we haven't found in this way, but I don't see any flat earth model that would allow this kind of circumnavigation.
  #15  
Old 10-15-2018, 10:28 AM
Alpha Twit's Avatar
Alpha Twit Alpha Twit is offline
Guest
 
Join Date: Jun 2009
Location: Somewhere south of normal
Posts: 1,634
Quote:
Originally Posted by Voyager View Post
In this case it is since we've circumnavigated the Earth both East-West and North-South, so we've exhausted the search space. We can't prove that there isn't a hole through the Earth we haven't found in this way, but I don't see any flat earth model that would allow this kind of circumnavigation.
No, according to Flat-Earth logic, that's no more definitive than if you said that someone you know saw Sasquatch, Santa Claus and the little dog from the old Taco Bell commercials downing tequila shooters at last year's cinco de mayo celebration. It's an anecdote. What kind of physical, tangible proof can you show me that you personally have made that journey? Oh, you have none? Well then you're just lying to support the conspiracy!
__________________
Somebody load the manatee cannon!
  #16  
Old 10-15-2018, 10:29 AM
Patch Patch is offline
Guest
 
Join Date: Aug 2005
Location: In my house
Posts: 1,759
Quote:
Originally Posted by bizerta View Post
Yesterday, on CBS Sunday Morning, they had a segment on flat-earthers. Are these people just ignorant or are they putting us on?
There are a lot of really stupid people out there.

CoolHardLogic has some wonderful YouTube videos debunking their nonsense, along with the geocentrists. They're fascinating to watch not just for the animation, but the elegant simplicity of the math and physics.
  #17  
Old 10-15-2018, 10:37 AM
bizerta bizerta is offline
Guest
 
Join Date: Dec 1999
Location: wilmington, ma
Posts: 862
Quote:
Originally Posted by Munch View Post
They deny this proof by saying that the moon is self-illuminating, and that lunar eclipses are the moon cycling through something. It's irrefutable in its pure lunacy. Those are the arguments that I think are good at just being able to point at the flat earth movement and hold them up as crackpots. ...
OP here. When they interviewed some of these nuts, they also said that the moon landing was a hoax, so no one is on the moon to create the illusion of an eclipse "cycling". How do these whack-a-doodles explain how we know, in advance, when a lunar eclipse will occur.
  #18  
Old 10-15-2018, 11:10 AM
Gorsnak Gorsnak is online now
Charter Member
 
Join Date: Jan 2003
Location: Saskaboom
Posts: 9,039
Quote:
Originally Posted by Munch View Post
They deny this proof by saying that the moon is self-illuminating, and that lunar eclipses are the moon cycling through something. It's irrefutable in its pure lunacy. Those are the arguments that I think are good at just being able to point at the flat earth movement and hold them up as crackpots.

What I find to be a solid argument is time lapse photos of the stars from the northern hemisphere, the equator, and the southern hemisphere, side-by-side-by-side. [emphasis added]
You might not have intended that pun, but it's the best one ever.
  #19  
Old 10-15-2018, 11:12 AM
pulykamell pulykamell is online now
Charter Member
 
Join Date: May 2000
Location: SW Side, Chicago
Posts: 45,337
Quote:
Originally Posted by Bullitt View Post
Thatís not a definitive proof.
Is there even a point to looking for a "definitive proof" for flat-Earthers? Just for fun, I looked up what they believe the edge is. Apparently, it's an ice shelf, Antarctica. Like this.
  #20  
Old 10-15-2018, 11:19 AM
Czarcasm's Avatar
Czarcasm Czarcasm is online now
Charter Member
Charter Member
 
Join Date: Apr 1999
Location: Portland, OR
Posts: 57,941
Evidence gathered through the use of science is easily dismissed through the use of idiocy.
  #21  
Old 10-15-2018, 11:19 AM
Machine Elf Machine Elf is online now
Guest
 
Join Date: Feb 2007
Location: Challenger Deep
Posts: 11,385
Quote:
Originally Posted by Bullitt View Post
Thatís not a definitive proof.
https://wiki.tfes.org/The_Ice_Wall

The claim is that the ice wall is the "edge" of the known world, and that whatever is beyond it is unknown.

Quote:
Originally Posted by The Flat Earth Society Wiki
Beyond the 150 foot Ice Wall is anyone's guess. How far the ice extends; how it terminates; and what exists beyond it, are questions to which no present human experience can reply. All we at present know is, that snow and hail, howling winds, and indescribable storms and hurricanes prevail; and that in every direction "human ingress is barred by unsealed escarpments of perpetual ice," extending farther than eye or telescope can penetrate, and becoming lost in gloom and darkness. Some hold that the tundra of ice and snow stretches forever eternally.
.
.
.
Temperatures are thought to approach absolute zero the further one explores outwards. Exploration in this type of pitch black freezing environment is impossible for any man or machine. We live on a vast plane with an unknown diameter and an unknown depth. Dr. Samuel Birley Rowbotham held that knowing the true dimensions of the earth may be something that is forever unknowable by man.
They don't list an explanation for why a transantarctic flight can start at the coast on one one side of Antarctica and then arrive at the coast on the far side of the continent. This is something that should be impossible according to the flat earth model.

To be fair, this isn't a simple test available to us common folk.

If you actually did it, your observations would be dismissed by any flat-earther who wasn't on that flight with you. They'd cite some kind of navigational error, saying you actually flew on some kind of long arc that brought you back out to the coast somewhere else along the edge of the world.

If you offered to take a flat-earther with you, they'd likely decline, since (according to their model) your flight would never return. On the off-chance you managed to convince one to come with you, they'd again cite navigational error as the reason for your safe return to the known world.

An alternative: Circumnavigate Antarctica, hugging the coastline and measuring distance traveled. By the spherical-earth model, the distance should be about 8900 miles. By the flat-earth model, it should be more like 50,000 miles. They could claim some kind of speed/distance measurement error, but they'd have to explain why it would be so repeatable - by different planes/navigators/pilots. Eventually they'd have to fall back to their old standby, claiming a vast conspiracy theory. At which point you have to admit there's nothing you can do. The kinds of people who believe in conspiracy theories are the kinds of people who can never be convinced of the truth of anything that casts doubt on their conspiracy theory - no matter how big and implausible the conspiracy theory may be.
  #22  
Old 10-15-2018, 12:25 PM
DPRK DPRK is offline
Guest
 
Join Date: May 2016
Posts: 2,129
Quote:
Originally Posted by Machine Elf View Post
https://wiki.tfes.org/The_Ice_Wall

The claim is that the ice wall is the "edge" of the known world, and that whatever is beyond it is unknown.
It's plenty known. Haven't you read At the Mountains of Madness ?
  #23  
Old 10-15-2018, 12:28 PM
Munch Munch is offline
Guest
 
Join Date: Mar 2000
Location: Parts Unknown
Posts: 22,129
Quote:
Originally Posted by bizerta View Post
OP here. When they interviewed some of these nuts, they also said that the moon landing was a hoax, so no one is on the moon to create the illusion of an eclipse "cycling". How do these whack-a-doodles explain how we know, in advance, when a lunar eclipse will occur.
No - some of them believe that the moon is semi-transparent, and cycles through various iterations of the moon phases.

Quote:
Originally Posted by Gorsnak View Post
You might not have intended that pun, but it's the best one ever.
  #24  
Old 10-15-2018, 12:32 PM
septimus's Avatar
septimus septimus is offline
Guest
 
Join Date: Dec 2009
Location: The Land of Smiles
Posts: 17,549
I refer Honorable Doper to the answer I gave when this question was posed almost six years ago:

Quote:
Originally Posted by Antonio Pigafetta, one of 18 first to circumnavigate the Earth

ďOn Wednesday, the ninth of July [1522], we arrived at one of these islands named Santiago, where we immediately sent the boat ashore to obtain provisions. [...] And we charged our men in the boat that, when they were ashore, they should ask what day it was. They were answered that to the Portuguese it was Thursday, at which they were much amazed, for to us it was Wednesday, and we knew not how we had fallen into error. For every day I, being always in health, had written down each day without any intermission. But, as we were told since, there had been no mistake, for we had always made our voyage westward and had returned to the same place of departure as the sun, wherefore the long voyage had brought the gain of twenty-four hours, as is clearly seen.Ē
  #25  
Old 10-15-2018, 12:34 PM
GaryM's Avatar
GaryM GaryM is offline
Charter Member
 
Join Date: Jun 2000
Location: St. Louis, MO 50mi. West
Posts: 4,891
People all over the globe believe that the earth is flat.

GaryM
__________________
GaryM
  #26  
Old 10-15-2018, 12:50 PM
Shoeless's Avatar
Shoeless Shoeless is offline
Charter Member
 
Join Date: Jan 2003
Location: The Sunflower State
Posts: 6,218
Quote:
Originally Posted by Alpha Twit View Post
No, according to Flat-Earth logic, that's no more definitive than if you said that someone you know saw Sasquatch, Santa Claus and the little dog from the old Taco Bell commercials downing tequila shooters at last year's cinco de mayo celebration. It's an anecdote. What kind of physical, tangible proof can you show me that you personally have made that journey? Oh, you have none? Well then you're just lying to support the conspiracy!
By that logic, you could just as easily call bullshit on their Flat Earth theory. "Have you been to the edge? Have you seen it with your own eyes? Then you have no proof that the Earth is flat and you're just lying to support the conspiracy!"
  #27  
Old 10-15-2018, 12:56 PM
DCnDC's Avatar
DCnDC DCnDC is offline
Member
 
Join Date: Feb 2010
Location: The Dueling Grounds
Posts: 11,193
Quote:
Originally Posted by bizerta View Post
Yesterday, on CBS Sunday Morning, they had a segment on flat-earthers. Are these people just ignorant or are they putting us on?
I was always under the impression it was an attempt to shoehorn religion into science, or vice-versa.
  #28  
Old 10-15-2018, 01:45 PM
CookingWithGas's Avatar
CookingWithGas CookingWithGas is online now
Charter Member
 
Join Date: Mar 1999
Location: Tysons Corner, VA, USA
Posts: 12,493
Quote:
Originally Posted by bizerta View Post
I was once on a cruise ship at sea on a pristine cloudless evening. As I stood on the deck, I watched the sun disappear below the horizon. As soon as the sun vanished, I ran up a flight to the next deck and witnessed the sun setting again about 10 seconds later.
There are lots of way to demonstrate a spheroid Earth but this is not one of them. As the sun disappears past the edge of a flat Earth, naturally taking a higher vantage point would allow you to see the sun again.

When a ship is sighted at the horizon, first the top of its mast is visible then gradually the lower parts of the ship become visible. If Earth were flat you would see the whole ship as soon as you could see any of it.
__________________
Making the world a better place one fret at a time.
| | |∑| |∑| |∑| |∑| | |:| | |∑| |∑|
  #29  
Old 10-15-2018, 02:01 PM
Alpha Twit's Avatar
Alpha Twit Alpha Twit is offline
Guest
 
Join Date: Jun 2009
Location: Somewhere south of normal
Posts: 1,634
Quote:
Originally Posted by Shoeless View Post
By that logic, you could just as easily call bullshit on their Flat Earth theory. "Have you been to the edge? Have you seen it with your own eyes? Then you have no proof that the Earth is flat and you're just lying to support the conspiracy!"
Agreed, the problem is that they're used to being called on their bull and are completely unfazed by it. They know, with absolute perfect clarity, what the Truth is. At best, anyone who disagrees with them is just simply mistaken. There is no amount of logic, facts, science, historical or photographic evidence or personal testimonial that can sway them from their world view. It's useless to attempt to sway their views on this matter and I waste no time on the attempt.
__________________
Somebody load the manatee cannon!
  #30  
Old 10-15-2018, 02:09 PM
Munch Munch is offline
Guest
 
Join Date: Mar 2000
Location: Parts Unknown
Posts: 22,129
Quote:
Originally Posted by Shoeless View Post
By that logic, you could just as easily call bullshit on their Flat Earth theory. "Have you been to the edge? Have you seen it with your own eyes? Then you have no proof that the Earth is flat and you're just lying to support the conspiracy!"
That's where they want to take the conversation. It's all a conspiracy, and the "fact" that access to "Antarctica" is heavily regulated by international treaty is proof enough to all of them that the Rothschilds are all in control (or whatever).
  #31  
Old 10-15-2018, 02:19 PM
wolfpup's Avatar
wolfpup wolfpup is offline
Guest
 
Join Date: Jan 2014
Posts: 9,357
I wonder how flat earthers explain the fact that the moon appears upside down when seen from Australia, compared to how it looks from the northern hemisphere.
  #32  
Old 10-15-2018, 03:58 PM
Chronos's Avatar
Chronos Chronos is online now
Charter Member
Moderator
 
Join Date: Jan 2000
Location: The Land of Cleves
Posts: 79,433
Hm, it sure was nice of the Rothschilds to let my mom (a retired elementary-school teacher) visit Antarctica a few years back, then.
  #33  
Old 10-15-2018, 04:35 PM
scr4 scr4 is offline
Member
 
Join Date: Aug 1999
Location: Alabama
Posts: 14,920
If you really want to know what they believe, the Oh no, Ross and Carrie! podcast did interviews of Mark Sargent and Jeran Campanella. They also participated in some meetings and experiments with flat earthers - just search their web site for "flat earth."

I think Mark Sargent seemed to imply that the sky is a giant artificial display that can show the stars, Moon, etc in any way they want us to see them. I remember Ross asking if it was like a lenticular display, showing different things depending on view angle, and he basically said yes. With this explanation they can dismiss pretty much any argument based on observing the sky.
  #34  
Old 10-15-2018, 05:07 PM
cormac262 cormac262 is offline
Member
 
Join Date: Feb 2003
Location: San Diego, CA
Posts: 1,310
My girlfriend's brother works with a guy who is a flat-earther. So much so that his daughter caused a stir in school by confronting her teacher who was showing a spherical earth.
This guy has been dying to "discuss" his view with me - with the challenge for me to prove him wrong.

I've given this a lot of thought, and even checked out the flat earth website (there are SO many questions about that model, and you need to have some "basis" or foundation from which to start any counter-arguments).
I decided two things:
1) that to prove that the earth is round might be "too much". So I decided to focus on dis-proving the flat earth model. I figured if I could poke holes in his view, he would then be open to the truth and see how none of the failings are valid with the true model.
2) it would be best to dis-prove his view with observations that he could see/confirm personally. He would not have to trust anything other than his own experience. (no trusting those "faked" NASA photos, etc.)

My first thought was "if the earth were flat, why would there be a need for time zones ?" That is, a flat earth would all experience the same "day" and "night". But the flat-earthers have an explanation for that: the sun is a LOT closer than you think, and in being so close, the "daylight" is focused on only parts of the (flat) earth at a time.

I considered the eclipse idea (with the flat earth model, it is unclear "what" causes lunar eclipses). But this would require having him observe a lunar eclipse, and this could take a while.

So my next idea was kind of an inverse of Eratosthenes' approach. Being that the flat-earther is in the northern hemisphere, I was going to have him measure the angle from the horizon to the North Star (I even made a crude sextant for him) at different locations (one where he lives, one several hundred miles south). IF he believed the North Star to be "far enough" away, then the angles (his latitude) would be different. This could not be with a flat earth.
Again using the North Star, if I could get him to travel south of the equator, I was going to have him confirm that he could no longer see the North Star. But this was a bit trickier in that it might be tougher to find "reference stars" to "point to" the North Star (or where it should be) as well. I thought this might be too prone to error to be conclusive.
  #35  
Old 10-15-2018, 05:07 PM
jasg jasg is online now
Charter Member
 
Join Date: Nov 2001
Location: Upper left hand corner
Posts: 5,460
Quote:
Originally Posted by Alpha Twit View Post
Lunar eclipses

As the Earth passes between the Sun and Moon, it always produces a circular shadow. It's not possible for a flat, disk like Earth to always produce such a shadow. Only a nearly spherical world can do that.
You must have missed this eclipse photo
  #36  
Old 10-15-2018, 05:24 PM
scr4 scr4 is offline
Member
 
Join Date: Aug 1999
Location: Alabama
Posts: 14,920
Quote:
Originally Posted by cormac262 View Post
1) that to prove that the earth is round might be "too much". So I decided to focus on dis-proving the flat earth model. I figured if I could poke holes in his view, he would then be open to the truth and see how none of the failings are valid with the true model.
The problem with this approach is, disproving one flat-earth model does not prove a round/spherical earth.

Quote:
My first thought was "if the earth were flat, why would there be a need for time zones ?" That is, a flat earth would all experience the same "day" and "night". But the flat-earthers have an explanation for that: the sun is a LOT closer than you think, and in being so close, the "daylight" is focused on only parts of the (flat) earth at a time.
Yes, their model usually shows the sun hovering over the flat earth, like this. That link also discusses problems with this model, so that's a good start. Major points being: how do they explain sunsets? And how do they explain why the Sun doesn't get bigger mid-day?

That last point is easy to measure. Just rig up a simple pinhole projector.


Quote:
IF he believed the North Star to be "far enough" away, then the angles (his latitude) would be different. This could not be with a flat earth.
Wouldn't work, they think the night sky is a dome above the flat earth.
  #37  
Old 10-15-2018, 05:43 PM
Alpha Twit's Avatar
Alpha Twit Alpha Twit is offline
Guest
 
Join Date: Jun 2009
Location: Somewhere south of normal
Posts: 1,634
Quote:
Originally Posted by cormac262 View Post
This guy has been dying to "discuss" his view with me - with the challenge for me to prove him wrong.
Your reply doesn't need to go any farther than Hitchens razor.
__________________
Somebody load the manatee cannon!
  #38  
Old 10-15-2018, 06:13 PM
Iggins Iggins is offline
Guest
 
Join Date: Feb 2005
Location: Brewtown, Oregon
Posts: 1,020
Have there been any "prominent" flat-earthers that have renounced their views? Such a person could help explain the thought process both for believing and non-believing.
  #39  
Old 10-15-2018, 06:45 PM
Napier Napier is offline
Charter Member
 
Join Date: Jan 2001
Location: Mid Atlantic, USA
Posts: 9,211
Quote:
Originally Posted by CookingWithGas View Post
[...]

When a ship is sighted at the horizon, first the top of its mast is visible then gradually the lower parts of the ship become visible. If Earth were flat you would see the whole ship as soon as you could see any of it.
I have heard this many times, but when I try to verify it, it never works. The horizon and distant objects are indistinct for too many reasons, such as haze. Have you actually tried this?

I believe the earth is round, I just don't think this demo works well enough to use.
  #40  
Old 10-15-2018, 08:19 PM
rat avatar's Avatar
rat avatar rat avatar is online now
Member
 
Join Date: Dec 2009
Location: Seattle, Wa
Posts: 4,705
Quote:
Originally Posted by Napier View Post
I have heard this many times, but when I try to verify it, it never works. The horizon and distant objects are indistinct for too many reasons, such as haze. Have you actually tried this?

I believe the earth is round, I just don't think this demo works well enough to use.

At 6' the distance to the horizon is ~3 miles, which is pretty easy to demonstrate.
  #41  
Old 10-15-2018, 09:37 PM
Sloe Moe Sloe Moe is offline
BANNED
 
Join Date: Jul 2018
Posts: 380
Beside the Erathosthenes work, an ordinary straight line traverse 500 to 1000 kilometers long should show that your points, adjusted to sea level, will no longer be aligned in a cross section.
  #42  
Old 10-15-2018, 10:11 PM
septimus's Avatar
septimus septimus is offline
Guest
 
Join Date: Dec 2009
Location: The Land of Smiles
Posts: 17,549
Quote:
Originally Posted by cormac262 View Post
My first thought was "if the earth were flat, why would there be a need for time zones ?" That is, a flat earth would all experience the same "day" and "night". But the flat-earthers have an explanation for that: the sun is a LOT closer than you think, and in being so close, the "daylight" is focused on only parts of the (flat) earth at a time.
See #24. In what flat-earth model can you lose an entire day just by traveling?
  #43  
Old 10-15-2018, 10:12 PM
beowulff's Avatar
beowulff beowulff is online now
Member
 
Join Date: May 2001
Location: Scottsdale, more-or-less
Posts: 15,989
Quote:
Originally Posted by cormac262 View Post
My girlfriend's brother works with a guy who is a flat-earther. So much so that his daughter caused a stir in school by confronting her teacher who was showing a spherical earth.
This guy has been dying to "discuss" his view with me - with the challenge for me to prove him wrong.

I've given this a lot of thought, and even checked out the flat earth website (there are SO many questions about that model, and you need to have some "basis" or foundation from which to start any counter-arguments).
I decided two things:
1) that to prove that the earth is round might be "too much". So I decided to focus on dis-proving the flat earth model. I figured if I could poke holes in his view, he would then be open to the truth and see how none of the failings are valid with the true model.
2) it would be best to dis-prove his view with observations that he could see/confirm personally. He would not have to trust anything other than his own experience. (no trusting those "faked" NASA photos, etc.)

My first thought was "if the earth were flat, why would there be a need for time zones ?" That is, a flat earth would all experience the same "day" and "night". But the flat-earthers have an explanation for that: the sun is a LOT closer than you think, and in being so close, the "daylight" is focused on only parts of the (flat) earth at a time.

I considered the eclipse idea (with the flat earth model, it is unclear "what" causes lunar eclipses). But this would require having him observe a lunar eclipse, and this could take a while.

So my next idea was kind of an inverse of Eratosthenes' approach. Being that the flat-earther is in the northern hemisphere, I was going to have him measure the angle from the horizon to the North Star (I even made a crude sextant for him) at different locations (one where he lives, one several hundred miles south). IF he believed the North Star to be "far enough" away, then the angles (his latitude) would be different. This could not be with a flat earth.
Again using the North Star, if I could get him to travel south of the equator, I was going to have him confirm that he could no longer see the North Star. But this was a bit trickier in that it might be tougher to find "reference stars" to "point to" the North Star (or where it should be) as well. I thought this might be too prone to error to be conclusive.
Really, the only "proof" you need is a cell phone with GPS. If he is reasonably intelligent, ask him how the GPS timing would work for anything but a spherical Earth.
  #44  
Old 10-15-2018, 10:23 PM
x-ray vision's Avatar
x-ray vision x-ray vision is offline
Charter Member
 
Join Date: Oct 2002
Location: N.J.
Posts: 5,812
UNDENIABLE! One Simple & Fatal Flaw of the Flat Earth "Model"
  #45  
Old 10-15-2018, 10:25 PM
Xema Xema is offline
Guest
 
Join Date: Mar 2002
Posts: 11,900
Quote:
Originally Posted by Napier View Post
Have you actually tried this?
While in the Navy, I spent a decent amount of time on a ship at sea. The phenomenon of seeing a distant ship "hull down" (i.e. with only its superstructure visible above the horizon), then watching the whole ship become visible as it gets closer is something encountered dozens of times a day. As distance increases, the opposite effect is noted, until all that's visible is the very highest point on the ship, then nothing.

As you'd expect, lookouts stationed well above the water routinely see further. From a lower place, you'll reliably see less of a distant ship (or island, or building on the shore, or anything else).


To be sure, on some days poor visibility (rain, fog, etc.) interferes with this. But in general it's clear, apparent, obvious and unmistakable - not in any way subtle, obscure or mysterious.
  #46  
Old 10-15-2018, 10:55 PM
Xema Xema is offline
Guest
 
Join Date: Mar 2002
Posts: 11,900
Perhaps the simplest demonstration of the failure of all flat-earth models is a video of the night sky looking south in the southern hemisphere (see 1:32 in this video). You clearly see all the stars rotating around the southern celestial pole - which flat-earth models say is impossible.

Last edited by Xema; 10-15-2018 at 10:57 PM.
  #47  
Old 10-15-2018, 11:27 PM
Little Nemo Little Nemo is online now
Charter Member
 
Join Date: Dec 1999
Location: Western New York
Posts: 78,855
The simplest demonstration that the Earth is a sphere is to get yourself a good pair of shoes and a swimsuit and start traveling in a straight line. No matter which direction you choose, you will end up back at your starting point without ever having encountered an edge.
  #48  
Old 10-15-2018, 11:33 PM
beowulff's Avatar
beowulff beowulff is online now
Member
 
Join Date: May 2001
Location: Scottsdale, more-or-less
Posts: 15,989
Quote:
Originally Posted by Xema View Post
Perhaps the simplest demonstration of the failure of all flat-earth models is a video of the night sky looking south in the southern hemisphere (see 1:32 in this video). You clearly see all the stars rotating around the southern celestial pole - which flat-earth models say is impossible.
Nah, it's all due to refraction.
Refraction explains everything.
  #49  
Old 10-15-2018, 11:39 PM
DPRK DPRK is offline
Guest
 
Join Date: May 2016
Posts: 2,129
If you are going to rely on geometric arguments, no need to navigate all the way around the Earth. Just mark off a reasonably big triangle and sum up its angles....
  #50  
Old 10-15-2018, 11:40 PM
scr4 scr4 is offline
Member
 
Join Date: Aug 1999
Location: Alabama
Posts: 14,920
Quote:
Originally Posted by septimus View Post
See #24. In what flat-earth model can you lose an entire day just by traveling?
In the standard flat-earth model.
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 03:57 PM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2018, vBulletin Solutions, Inc.

Send questions for Cecil Adams to: cecil@straightdope.com

Send comments about this website to: webmaster@straightdope.com

Terms of Use / Privacy Policy

Advertise on the Straight Dope!
(Your direct line to thousands of the smartest, hippest people on the planet, plus a few total dipsticks.)

Copyright © 2018 STM Reader, LLC.

 
Copyright © 2017