April 1, 2007 Issue

Physics To Go 22 - Big shadow/color shift

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Physics in Your World

Atmospheric Optics:  Rays and Shadows image
photo credit: Michael Connelley; image source

Atmospheric Optics: Rays and Shadows

In this image (hi-res version), the sun is behind the camera, opposite the full moon (as usual).  The mountain casts a shadow about 300 miles long, so we are looking down a shadow-tunnel. In the photo, the edges of the shadow converge due to perspective--it's like looking at railroad tracks that seem to meet in the distance. To learn more about mountain shadows, see Moonrise Through Mauna Kea's Shadow and the Shadow of Mount Rainier. For related images, see Atmospheric Optics:  Rays and Shadows.

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Physics at Home

Web Cite

Check out The Floyss, computer-generated creatures that swarm, hosted by the Cité des Sciences et de l'Industrie. You can set properties such as collision distance, acceleration, number of neighbors, and free will factor. To get there, go to Web Cite, and look for "The Floyss" under "Biology".


From Physics Research

Tuning the Sun’s Rays image
photo credit: Stanislav Balouchev; image source

Tuning the Sun’s Rays

The photo (hi-res version) shows an intense beam of filtered sunlight (green) which is "up-converted" to blue light (this process is called up-conversion because blue light has a higher frequency than green light). To learn how it's done, see Tuning the Sun's Rays from the American Physical Society's Physical Review Focus. You can find out how frequency is related to photon energy at Physics 2000's Plank's Constant and the Energy of a Photon, and for more, visit the rest of the Quantum Atom section on the same site.

Worth a Look

Physics 2000

Visit Physics 2000 for an engaging overview of concepts in modern physics. You can learn about atoms, light, radioactivity and more through helpful articles and applets, and see how the concepts led to technology we use today.

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