Sunday, August 6, 2017

Native Americans in a Lunar Eclipse by William Rimmer (American artist, 1816-1879)

William Rimmer (American artist, 1816-1879) Native Americans in a Lunar Eclipse. Every year, there are at least 2 lunar eclipses and as many as 5, although total lunar eclipses are significantly less common. A lunar eclipse always occurs about 2 weeks before or after a solar eclipse. On some occasions, a lunar eclipse can be both preceded and followed by a solar eclipse.  A lunar eclipse occurs when the Moon passes directly behind the Earth into its umbra (shadow). This can occur only when the sun, Earth, and moon are aligned (in "syzygy") exactly, or very closely so, with the Earth in the middle. Hence, a lunar eclipse can occur only the night of a full moon. The type and length of an eclipse depend upon the Moon's location relative to its orbital nodes.  A total lunar eclipse has the direct sunlight completely blocked by the earth's shadow. The only light seen is refracted through the earth's shadow. This light looks red for the same reason that the sunset looks red, due to rayleigh scattering of the more blue light. Because of its reddish color, a total lunar eclipse is sometimes called a blood moon.