The Sep 27/28 Lunar eclipse was intently watched all over the world for it was a rare occurrence indeed. It was a total lunar eclipse, which was a part of a series of eclipses called a tetrad, at a time when it was closest to the earth in its orbiting path.
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Only about one in three lunar eclipses are total lunar eclipses. Every once in a while, four total lunar eclipses happen in a row. This is called a lunar tetrad.
According to NASA, the current century – 2001 to 2100 – will have eight tetrads. They have only occurred 5 times in the 1900s -1910,1928,1946,1964,1982
Fig: Total lunar eclipse
A supermoon is the coincidence of a full moon or a new moon with the closest approach the Moon makes to the Earth on its elliptical orbit, resulting in the largest apparent size of the lunar disk as seen from Earth. The term “supermoon” is not astronomical, but originated in modern astrology. The technical name is the perigee–syzygy of the Earth-Moon-Sun system. A full moon at perigee is visually larger up to 14% in diameter (or about 30% in area) and shines 30% more light than one at its farthest point, or apogee.
Blood Moon is not really a scientific term either and 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
The red color of the moon is due to the Rayleigh scattering of sunlight through the Earth’s atmosphere, the same effect that causes sunsets to appear red
Like solar eclipses, lunar eclipses tend to occur in 18 year long cycles called Saros cycles. Lunar eclipses separated by a Saros cycle share similar features, including time of the year and the distance of moon from earth. Eclipses that are separated by a Saros cycle are included in a Saros series.
The September 27/ 28, 2015 Lunar Eclipse belonged to Saros Series 137. It was the 28th eclipse and the last total lunar eclipse in a series of 81 lunar eclipses. The series began with a penumbral eclipse on December 17, 1564 and will end with another penumbral eclipse on April 20, 2953.
The next Super moon eclipse of the tetrad is slated to happen on October 8, 2033.
Author: Dr Sona Sharma