enter image description here

During the recent SpaceX CRS-12 launch which was broadcast live on YouTube, it appeared at one point as if the horizon of the earth was completely flat.

What caused this to happen?

  • 12
    $\begingroup$ Stab in the dark; camera lens angle. $\endgroup$ Aug 14, 2017 at 18:38
  • $\begingroup$ I'm curious if there's some sort of camera-lens simulator for different altitudes. $\endgroup$
    – Nick T
    Aug 14, 2017 at 22:52
  • 3
    $\begingroup$ perspective. And limited field of view. $\endgroup$ Aug 15, 2017 at 13:12
  • $\begingroup$ What makes a really long arc look like a straight line? $\endgroup$
    – Octopus
    Aug 15, 2017 at 17:12
  • 1
    $\begingroup$ This seems to be good evidence that the Earth is actually flat $\endgroup$
    – Richard
    Aug 15, 2017 at 17:47

1 Answer 1


I suspect it is a combination of the fisheye effect of the camera lens and the lack of altitude.

The fisheye effect is well known for making the earth appear more round than it should be. It does so by curving seemingly straight lines towards the center of the image, with greater effect the further from the center. Take the opposing camera angle from the same launch: enter image description here

Here, the fisheye effect makes the earth more curved than usual as the curvature of the earth is added to the curvature due to the wide-angle lensing. Since in your screenshots, the earth is in the corner away from the centerpoint, the fisheye effect tries to reverse what curvature there was away from the center, the net effect making the earth flat.

Also, at an altitude of ~200km, the curvature of the earth is not very apparent. Even with the naked eye, you would only notice the curvature due to your wide angle of vision.

  • 6
    $\begingroup$ The 77km figure in OP's screenshot is coming from stage 1 telemetry; stage 2 would be ~200km up at this point in the flight. $\endgroup$ Aug 14, 2017 at 20:48
  • 11
    $\begingroup$ For a comparison that maybe helps, if you compare the Earth with a soccer ball, 200km equates to a "height" of about 3mm. $\endgroup$ Aug 15, 2017 at 1:06
  • 3
    $\begingroup$ @MartinArgerami: Kerbal Space Project says you are lying! $\endgroup$
    – Zaibis
    Aug 15, 2017 at 7:46
  • 5
    $\begingroup$ @Zaibis For reference, Kerbin has a radius of 600 km. The Earth has a radius of 6371 km. $\endgroup$
    – JSQuareD
    Aug 15, 2017 at 12:21
  • 3
    $\begingroup$ @JSQuareD: Pah, and next you try to tell me our Mun isn't ~1.400.000 KM away from earth. $\endgroup$
    – Zaibis
    Aug 15, 2017 at 12:23

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