September 16, 2006 Issue

Physics To Go 9 - Pinhole image/contrails

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Physics in Your World

Bob Miller's Light Walk image
photo credit: Nils van der Burg

Bob Miller's Light Walk

These pinhole images of the sun, made by the small openings between leaves, show a nearly-total solar eclipse. For more about pinhole images, see Bob Miller's Light Walk and Pinhole Investigations (both Exploratorium sites).

This feature was updated on July 4, 2013.

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Physics at Home


This guide provides activities to develop training in astronomy, atmospheric science, geology, and biology, all part of a mission to design a planet tailor-made for life.

For more on the habitability of planet Earth, see Life on Earth and Elsewhere.


From Physics Research

Contrails image
image credit: National Oceanic and Atmospheric Administration/Department of Commerce


The false-color image above shows jet contrails in the skies above the mid-Atlantic coast on 1/26/2001. Check out this photo taken on the ground at about the same time.

When U.S. commercial air traffic was grounded following the 9/11 attacks, atmospheric scientists took advantage of this opportunity to investigate the effect of jet contrails on Earth's climate. The results showed that contrails produced cooler days--more sunlight was reflected from the contrails--and warmer nights--more heat radiated from Earth was trapped (this trapping is the greenhouse effect).

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Sport Science

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