The stick "appears to bend," he said. "That is due to refraction. As light passes through the water it is refracted. The same thing happens to light waves in the atmosphere; they are bent in the direction of the moon."
The atmosphere scatters most of the short wavelengths of light—blue, green, and yellow—out of the refracted light leaving primarily orange and red wavelengths to reach the moon, thus its orange-reddish glow.
Fire Effect?
The more dust that is in the air—whether from volcanic eruptions, forest fires, or the build up of pollution—the more refracted light scatters. As a result, less light reaches the moon.
Espenak said the moon during this particular eclipse could be darker than originally anticipated, owing to an unexpected increase of particulate matter in the atmosphere from the forest fires that recently scorched nearly 800,000 acres (325,000 hectares) of land in California.
"It depends on how much dust these fires in California [threw] up in the atmosphere," he said.
Reynolds said he does not expect the fires to darken the eclipse owing to the time span between the fires and the eclipse.
Last in a Series
"The most unusual thing about this particular eclipse is that it is the last total eclipse in the Saros series that began in 1769 and recurred every 18 years and 11 days," said Fred Espenak.
A Saros series is a natural rhythm in the occurrence of similar eclipses. Each series typically lasts for 12 or 13 centuries and contains a total of 70 or more penumbral, partial, and total eclipses. At any given time there are approximately 40 different Saros series in progress.
Saturday's eclipse is the last total eclipse of Saros 126. The first total eclipse in the series was June 19, 1769. The series began with a partial eclipse on July 8, 1219 and will end with a partial eclipse on August 30, 2490.
|
SOURCES AND RELATED WEB SITES
|
