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I have seen already a couple of answers but none of them give an exact number of what should be the minimum height where we would be able to record the curvature of the earth

All I could find is minimum of 10km but you need a 60 degree viewing angle to see it... if that is true there is some amateur rocket footage out there with non fish eye lenses that show no curvature at 32km height do we need to go higher? if so how high exactly?

Here are the video's i'm talking about both go around 120,000 feet high. A high altitude balloon which uses some lens (most probably fish eye) and gives distort so not conclusive if what we see as a straight horizon is real http://youtube.com/watch?v=tvhFbvY_99o

the other is an amateur rocket launch at 2:13 http://youtu.be/qY7W3EMfrgc?t=133 The lens from a FlipHD camera as far as I can find out is between 42 and 48 degrees so much smaller then the 60 mentioned before the horizon is straight from the beginning of the launch but also when it reaches the top the horizon appears straight.

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    $\begingroup$ Possible duplicate of objects distorted by the earths curvature $\endgroup$
    – Carl Witthoft
    Commented Feb 5, 2016 at 12:57
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    $\begingroup$ This depends strongly on the subjective term "able to see the curvature". $\endgroup$
    – Carl Witthoft
    Commented Feb 5, 2016 at 12:58
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    $\begingroup$ Possible duplicate of How far into space does one have to travel to see the entire sphere of earth? $\endgroup$
    – Kyle Kanos
    Commented Feb 5, 2016 at 13:29
  • $\begingroup$ I agree with @CarlWitthoft: one can probably detect the curvature optically within a few feet with two mirrors and it might not even be a hard experiment to do. $\endgroup$
    – CuriousOne
    Commented Feb 5, 2016 at 15:30
  • $\begingroup$ All those articles are not answering the question about how high we need to be to see the horizon curving.. it's about the entire earth. $\endgroup$
    – Anti
    Commented Feb 5, 2016 at 16:42

2 Answers 2

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As a former sailor I can assure you that you can see the curvature of the earth from the crow's nest - all it takes is a calm sea.

Consider a light house that stands 50 meters above sea level. If you are in the crow's nest, say 25 meters above sea level), at what distance could you first spot the top of the light house on a calm day?

The problem is geometric - two posts sticking out from the surface of a large ball, and you want the tangent line to the ball that passes through the tips of both posts; start by considering how the central angle most close).

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  • $\begingroup$ I think the poster wants to see the horizon as curved laterally, not the effects of curvature on ranged objects. Your observations are, of course, correct, but these allow the earth's curvature to be deduced, not seen. $\endgroup$
    – WhatRoughBeast
    Commented Feb 5, 2016 at 16:31
  • $\begingroup$ yes im curious to know how high one needs to go with what type of lens to see the curvature.. $\endgroup$
    – Anti
    Commented Feb 5, 2016 at 16:43
  • $\begingroup$ The horizon presents itself as a circle when you are at sea; and approaching ships appear to rise up out of the water, the tops of the masts appearing first. Together these imply that ships at sea are on a curved surface, and that that surface is roughly spherical. Since you are measuring this from above the surface of the sea, it passes muster as an extrinsic rather than intrinsic measurement. The accuracy depends upon distance calibrations, calmness of the sea, etc. $\endgroup$
    – Peter Diehr
    Commented Feb 14, 2016 at 20:37
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In order to see the curvature, you need a 60 degree field of view and a cloud free day. From what I've read, you need to be about 35,000 feet above the surface. Find more information in this article here: http://www.howitworksdaily.com/how-high-do-you-have-to-go-to-see-the-curvature-of-the-earth/

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  • $\begingroup$ is 60 degree field of view a wide angle lense? and if so are these lenses always giving a distortion? $\endgroup$
    – Anti
    Commented Feb 5, 2016 at 16:40
  • $\begingroup$ You see where im going with this? I want to understand if the straight horizon seen on those 2 amateur high altitude camera's are a lense effect or are they are just not high enough to see it... $\endgroup$
    – Anti
    Commented Feb 5, 2016 at 16:44
  • $\begingroup$ Here are the video's im talking about a high altitude balloon which uses some lense (most probably fish eye) and gives distort so not conclusive if what we see as a straight horizon is real youtube.com/watch?v=tvhFbvY_99o the other is an amateur rocket launch at 2:13 you can see it's a normal lense I guess cause the horizon is straight from the beginning of the launch but also when it reaches the top... youtu.be/qY7W3EMfrgc?t=133 $\endgroup$
    – Anti
    Commented Feb 5, 2016 at 16:50
  • $\begingroup$ I don't know cameras well, but many pilots fly at 40,000 feet and still don't see curvature, so I believe the ability to see curvature depends on your placement on the globe. That, or seeing a "curve" is just an optical illusion at such a height. $\endgroup$
    – callisto
    Commented Feb 5, 2016 at 17:54
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    $\begingroup$ If I'm standing on a beach and hold up a straight edge to the horizon, surely I'll see the horizon falling away from the straight edge. Doesn't that demonstrate the curvature of the Earth? $\endgroup$
    – Peter4075
    Commented Feb 5, 2016 at 18:12

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