APOD
Astronomy Picture of the Day
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
Anticrepuscular Rays Over Wyoming
Explanation: What's happening over the horizon? Although the scene may appear somehow supernatural , nothing more unusual is occurring than a setting Sun and some well placed clouds. Pictured above are anticrepuscular rays . To understand them, start by picturing common crepuscular rays that are seen any time that sunlight pours though scattered clouds. Now although sunlight indeed travels along straight lines , the projections of these lines onto the spherical sky are great circles . Therefore, the crepuscular rays from a setting (or rising) sun will appear to re-converge on the other side of the sky. At the anti-solar point 180 degrees around from the Sun , they are referred to as anticrepuscular rays . Pictured above is a particularly striking set of anticrepuscular rays photographed last month near Cheyenne , Wyoming , USA .
| Date | February 21, 2012 |
|---|---|
| Credit | Image Credit & Copyright: Nate Cassell |
| Authors & editors: | Robert Nemiroff (MTU) & Jerry Bonnell (UMCP) |
| A service of: |
ASD at NASA / GSFC, NASA Science Activation & Michigan Tech. U. |



