The Blood Moon

The true �Blood moon� is synonymous with the Hunter�s moon, which is the first full moon after the Harvest Moon. The Harvest moon occurs when a full moon happens closest to the autumnal equinox. Contrary to popular belief, this Blood moon or Hunter�s moon has no connections to the blood-red moon that appears during a lunar eclipse.

In order to create a lunar eclipse, the Sun, Earth, and Moon must align exactly with the Earth in the middle. This way, the Earth blocks the Sun�s rays from the Moon and casts a shadow over it. There is always a full moon the night of a lunar eclipse because of this. As the Earth begins to cast its shadow on the Moon, the Moon changes color from gray to orange to shades of red. Hence, the common reference to the �Blood Moon� of a lunar eclipse. The color change comes from the penumbra�which is the less dark part of the Earth�s shadow�filtering out the blue light. As a result, the red light rays are still able to reach the Moon and turn it a bright color.

The shade of red depends on particles in the atmosphere at the time of the eclipse. For example, in the case of the recent June 15, 2011 total lunar eclipse, the Moon turned the deepest shade of red of the decade. Remnants of a volcanic ash cloud in Melbourne were attributed for this rare shade. A forest fire as well as a volcanic eruption can place tiny particles into the atmosphere that scatter blue and green light easily, but allow red light to pass through. Therefore, the deeper the color, the greater amount of dust or particles there is in the air. Red moons do not need to occur solely during a lunar eclipse though. Right after a fire, the Moon often has a red tinge. However, for the most dramatic and vivid color change, you must wait for a lunar eclipse.

Even though the Earth is big enough to block out the Sun, it doesn�t cause complete darkness on the Moon. Sunlight can bend around the edges of the Earth, which of course gets filtered by the atmosphere, but still reaches the Moon. If NASA follows through with the proposed permanent base on the Moon, astronauts would have quite an experience every time a lunar eclipse happens. From the perspective of the Moon, the Earth�s atmosphere lights up red and projects onto the Moon. This causes the Moon�s ground to actually glow red. If we aren�t given the opportunity to live on the Moon or to even just witness a lunar eclipse, then there is always the hope of seeing a Blood Moon at moonrise on a dusty, ashy night. Maybe one day it will occur on the night of the Hunter�s moon to cause a true Blood moon.

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