The Earth Is Not Flat: An Analysis of a Sunset Photo

Robert J. Vanderbei

Can a photo of the sunset over Lake Michigan reveal the shape of our planet?


figureA sunset over Lake Michigan on July 5, 2008.


figureA cropped and enlarged (4x) closeup of the blue channel.

There are several well-known ways to prove to yourself that the Earth is round—by looking at NASA images, watching ships disappear over the horizon, or noting the presence of time zones, which wouldn’t be possible without the longitudinal aspect of the planet. But did you know that you could reach the same conclusion simply by observing a sunset or sunrise over water on a calm, clear day? Moreover, from a photograph, you can even estimate, albeit rather crudely, the diameter of the Earth.

Log in or become a member to view the full text of this article.

This article may be available for purchase via the search at Optica Publishing Group.
Optica Members get the full text of Optics & Photonics News, plus a variety of other member benefits.

Add a Comment