This January 31 will see the second supermoon of this 2018. After the first, which was the morning of January 1 to 2, Tuesday night, 30 to Wednesday 31. But the supermoon is only one of the four phenomena that occur at the same time this January 31: there will also be a lunar eclipse, a moon of blood and a blue moon.
This coincidence has not occurred for 150 years, so this supermoon is quite special: the last time this extraordinary phenomenon took place was in 1866, and the next time it will be on January 31, 2037.
But what are these 4 phenomena dealt with?
Super moon
The orbit of the Moon is elliptical, and one side (apogee) is about 50,000 km. farther from the Earth than the closest one (perigee). Therefore, over the 28 days of the lunar cycle, the satellite is sometimes closer to us than others. The supermoon occurs when the moment of maximum approach is, in addition, the moment in which there is a full moon. A simple panorama can appreciate it between 10% and 15% larger than usual.
Blue Moon
A full moon is considered a "blue moon" when two full moons are produced in the same month. As this month of January has a full moon at the beginning of the month, another supermoon between January 1 and 2 this second full moon has been, in addition, a "blue moon".
Lunar eclipse
Also this January 31 a third phenomenon occurs, less common than the supermoon and the blue moon: an Earth, the Sun and the Moon are aligned, resulting in a total lunar eclipse. The full Moon coincides with the moment when the Moon enters the shadow of the Earth producing an eclipse.
The eclipse, however, will not be visible on the entire planet. In South America, Africa and Western Europe will not be seen, while in North America it will be visible before dawn on January 31. In Asia, Australia, New Zealand and eastern Russia, the total lunar eclipse will be visible.
Blood Moon
The last astronomical phenomenon that coincides this January 31 is the blood moon. During the course of the eclipse, the Earth's atmosphere will filter the blue and green light from the sun's rays, but it will instead pass the red one. That is why the moon will be dyed with the reflection of the reddish glow that will come from our atmosphere. Therefore, this moon of blood will only be visible in the parts of the planet where the eclipse can be seen.
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