Latest revision as of 03:32, 8 June 2026

The horizon dip measurement is the angle between the horizontal (the line perpendicular to the vertical at a specific point) and the apparent horizon.

On a globe, we would expect this angle to increase with increasing altitude, because the horizon would drop away with the curve.

On a flat earth, we would expect the horizon to always "rise to eye level".

This page is a gallery of photos showing the measured dip of the horizon from horizontal.

Instructions

If you want to submit your own image, email dip@mctoon.net Please include the following details with your submission:

1. A clearly visible horizon (ideally, no clouds at, or near the horizon)

2. An instrumented graphic overlay showing true horizontal

3. The name of the device generating the graphic overlay

3. Altitude at time of photo

4. Image Source/Credit. Please indicate if you want to be credited and how. We do not wish to dox anyone but we do want to appropriately give credit where it is due.

Gallery

Note:
Some photos are cropped due to the size limit for uploaded files.


Source/Credit	Globular EPIC Bikini @FlatSlugbrains on Twitter
Altitude	11074 m
Dip	3.3°
Device	Theodolite


Source/Credit	@Tylerthepilot_ on Twitter
Altitude	35820 m
Dip	4.8°
Device	Theodolite


Source/Credit	McToon
Altitude	35091 ft
Dip	~4°
Device	Theodolite


Source/Credit	@dwolfman54 on Twitter
Altitude	33709 ft
Dip	>2°
Device	Theodolite


Source/Credit	BK, flight from Newcastle to Brisbane, in Australia:
Altitude	36706 ft
Dip	~2°
Device	Theodolite


Source/Credit	Wolfie6020
Altitude	46000 ft
Dip
Device	cockpit display

@@ Line 1: / Line 1: @@
 The horizon dip measurement is the angle between the horizontal (the line perpendicular to the vertical at a specific point) and the apparent horizon.
-On a globe, you would expect this angle to increase with increasing altitude, because the horizon would drop away with the curve.
+On a globe, we would expect this angle to increase with increasing altitude, because the horizon would drop away with the curve.
-On a flat earth, if the plane is infinite, you would expect no drop of the horizon with increasing altitude. You would just be able to better resolve distant points because of the greater angular resolution between them.
+On a flat earth, we would expect the horizon to always "rise to eye level".
-Measurements will be forthcoming.
+This page is a gallery of photos showing the measured dip of the horizon from horizontal.
-{{#invoke:Math|precision|2}}
+= Instructions =
-'''Horizon Dip Calculator'''
+If you want to submit your own image, email dip@mctoon.net Please include the following details with your submission:
-The following calculator estimates the dip of the horizon based on altitude above Earth's surface.
-== Formula ==
+.  A clearly visible horizon (ideally, no clouds at, or near the horizon)
-\[
-\text{Dip} = \sqrt{\frac{2h}{R}}
-\]
-== Inputs ==
+.  An instrumented graphic overlay showing true horizontal
-* '''Altitude (h)''': Height above Earth's surface in meters.
-* '''Earth's radius (R)''': Approximate value is 6,371,000 meters.
-== Result ==
+.  The name of the device generating the graphic overlay
-\[
-\text{Result} = {{#expr:sqrt(2 * {{{altitude|0}}} / {{{radius|6371000}}})}}
-\]
-== Usage ==
+.  Altitude at time of photo
-{{HorizonDip
-| altitude = 1000
+.  Image Source/Credit.  Please indicate if you want to be credited and how.  We do not wish to dox anyone but we do want to appropriately give credit where it is due.
-| radius = 6371000
+= Gallery =
+'''Note:'''</br>Some photos are cropped due to the size limit for uploaded files.
+<div class="dip">
+{{Dip
+|image=File:Theodolite-app-flatslugbrains-.jpg
+|Source/Credit= Globular EPIC Bikini @FlatSlugbrains on Twitter
+|altitude=11074 m
+|dip=3.3°
+|device=Theodolite
+}}
+{{Dip
+|image=File:Tyler.jpg
+|Source/Credit= @Tylerthepilot_ on Twitter
+|altitude=35820 m
+|dip=4.8°
+|device=Theodolite
+}}
+{{Dip
+|image=File:Moon.jpg
+|Source/Credit=McToon
+|altitude=35091 ft
+|dip=~4°
+|device=Theodolite
+}}
+{{Dip
+|image=File:Theodolite-app-dwolfman54-.webp
+|Source/Credit=@dwolfman54 on Twitter
+|altitude=33709 ft
+|dip=>2°
+|device=Theodolite
 }}
+{{Dip
+|image=File:Theodolite-app-bk.webp
+|Source/Credit=BK, flight from Newcastle to Brisbane, in Australia:
+|altitude=36706 ft
+|dip=~2°
+|device=Theodolite
+}}
+{{Dip
+|image=File:Screenshot 2024-12-16 at 10.35.21 PM.png
+|Source/Credit=Wolfie6020
+|altitude=46000 ft
+|dip=
+|device=cockpit display
+}}
+</div>
+[[Category:Science data]]
+[[Category:Science]]