What is a Blood Moon?
Blood Moon is sometimes used to describe a Total Lunar Eclipse. When the Earth casts its shadow on a Full Moon and eclipses it, the Moon may get a red glow.
Total lunar eclipses are rare – only about one in three lunar eclipses are total. About four to five total eclipses can be seen at any place on Earth in a decade.
Lunar eclipses usually do not occur in any specific order. However, every once in a while, four total lunar eclipses happen in a row. This is called a lunar tetrad. The total lunar eclipses happen 6 months apart. There are at least six full Moons between two total lunar eclipses in a tetrad.
2014-2015 Lunar Tetrad
All four total lunar eclipses will be visible from most of the United States.
According to NASA, the current century – 2001 to 2100 – will have eight tetrads. The first tetrad of the 21st century took place in 2003, and the second will happen in 2014-2015. The first eclipses in each of these tetrads will occur between March and May.
Rare Series of Eclipses
Italian Astronomer Giovanni Schiaparelli calculated that the occurrence of such tetrads varies over centuries. Some 300 year intervals have several lunar tetrads, while other 300 year intervals do not have any. For example, the years between 1852 and 1908 did not have any tetrads, whereas the next 3 centuries will have 17 tetrads.
Blood Moons may Look Red
In recent years, the term Blood Moon has become popular when referring to Total Lunar Eclipses. When the Earth eclipses a full Moon, the direct sunlight is blocked, but the sun’s rays still light up the moon. This light, however, has travelled through the Earth’s atmosphere first, and sometimes causes the totally eclipsed Moon to look red or brownish.
Another End-of-the-world Prophecy?
Some people believe that the tetrad has special significance because the eclipses coincide with important Jewish festivals. The two April lunar eclipses in 2014 and 2015 occur at the same time asPassover, while the October and September eclipses occur during the Feast of Tabernacle. This, they suggest, is connected to a biblical prophecy of the end of times.
The fact is, eight of the tetrads since the first century have coincided with Jewish holidays without the world going under, so there is no reason to believe that the 2014-2015 tetrad will end the world this time either.