Blood Moon Lunar eclipse April 15
Look skyward early Tuesday morning and you will see a rare sight, the “Blood Moon”. This name has come into widespread use when describing the total lunar eclipses that will start happening tonight and will conclude in September, 2015. The description is not astronomically nor scientifically meaningful, but has gained gained colloquial acceptance in referring to specific types of full eclipses.
One reason why this is called a “Blood Moon” is because the full moon will glow with a reddish light during the eclipse.
The occurrence of four total eclipses in a row, during which the earth’s shadow completely covers the moon, is called a tetrad. The moon, instead of disappearing in the shadow, will shine with a coppery color, due to the sunlight refracted by the earth’s shadow.
This happens only rarely, sometimes merely once in 300 years. We are at a very unusual time for tetrads, in that another one will start in 2032, 18 years from now.
Giovanni Schiaparelli, the Italian astronomer who first saw the canals on Mars, figured out that these tetrads of eclipses occur in patterns of 300 year blocks. Some of these time periods have no tetrads (1852-1908) while others (2014-2314) will see 17 of them.
Another unusual aspect of tonight’s celestial event is that the best place to see the eclipse is finally North America. Our part of the earth, as well as the northern portion of South America, will line up exactly with the shadow being cast. In all other parts of the globe, the eclipse will be only partially visible, if seen at all.
Eclipses have long been held to have religious or spiritual meaning. The upcoming tetrads all align with religious holidays. The spring eclipses coincide with Passover, and the autumn events will happen during the Feast of the Tabernacle.