Empirical Earth · Shape, Curvature & the Horizon

How high must you go to see the curve?

The claim

“The horizon looks flat from a plane, and the curve in Felix Baumgartner’s jump is just fisheye distortion.”

What is measured

You can first make out the horizon’s curve near 10.7 km (35,000 ft), and it is obvious from the stratosphere. Felix jumped from 38,969.4 m, far above that point. More on refraction and the curve.

What would show this is wrong

a wide-field, optically corrected photo taken from above about 12 km, with the horizon through the center of the lens, that shows a dead-straight horizon.

Sources

  1. Refraction, Snell's law & refractive index of air/water. Standard optics; refractive index of air via the Ciddor/Edlén equations. E. Hecht, Optics ; NIST refractive-index references. Snell's link
  2. Red Bull Stratos — exit altitude 38,969.4 m (FAI-ratified). Felix Baumgartner, 14 Oct 2012; the curvature in the footage survives de-fishing the identified lens. Red Bull Stratos link
  3. Lynch, D. K., “Visually discerning the curvature of the Earth,” Applied Optics 47, H39–H43 (2008). Minimum altitude to detect horizon curvature by eye is at or just below 35,000 ft with a wi link
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