The internet is abuzz with news that the longest lunar eclipse of the 21st Century will take place on July 27, 2018. It will indeed be one of the longest total lunar eclipses of this century. Exciting, but there’s a small catch. To view this eclipse you have to be in the Eastern Hemisphere (Europe, Africa, Asia).
Unfortunately, in North America, the eclipse will be taking place during the midday and afternoon hours. By the time the Sun sets and the full Moon comes up over the horizon on the 27th, the eclipse will be long over. So this eclipse is for the folks who live on the other side of the world. Not for us. (Which, by the way, we mention on page 131 of your 2018 Farmers’ Almanac.)
If you live in or plan to travel to the Eastern Hemisphere, the Moon will appear directly overhead from a point only a few hundred miles off the east coast of Madagascar in the Indian Ocean.
What Is A Lunar Eclipse?
Lunar eclipses occur when the Earth passes between the Sun and Moon, and lines up precisely so that it blocks the Sun’s light, which otherwise reflects off the Moon. There are three types of lunar eclipses: total, partial and penumbral, with the most dramatic being a total lunar eclipse — when the Earth’s shadow totally covers the Moon. A lunar eclipse can occur only when there is a full Moon.
Why Will This S0-Called Longest Lunar Eclipse Last So Long?
The total phase will last 103 minutes, just four minutes shy of the absolute amount of time that the longest lunar eclipse is able to last.
The reason for the extreme duration is that the Moon tracks almost directly through the center of the Earth’s shadow. Because the Moon is also at apogee—its farthest point from Earth—on this very same day, it is moving at its slowest speed, and thus will take an inordinately long time to move through the Earth’s shadow. Much of Japan and eastern Australia will see the Moon set while in total eclipse. The central and eastern portions of South America will see the Moon rise either during or after totality. Unfortunately, no part of this eclipse will be visible from North or Central America.
Will This Lunar Eclipse Feature A Blood Moon (And is the World Ending)?
During a lunar eclipse, the Moon can sometimes turn red. The light reaching the Moon resembles the “color of blood,” but there is no way of predicting this in advance. So there are no grounds to call any particular lunar eclipse a “Blood Moon” until it actually shows its color. But when it does occur, the explanation is simple:
“During a total lunar eclipse, white sunlight hitting the atmosphere on the sides of the Earth gets absorbed and then radiated out (scattered). Blue-colored light is most affected,” NASA officials explained online. “That is, the atmosphere filters out (scatters away) most of the blue-colored light. What’s left over is the orange- and red-colored light.”
So a Moon turning red is nothing to fear. The only thing that happens during a lunar eclipse is that the Moon spends a couple of hours passing through the Earth’s shadow, hardly something to be concerned about.
When Can We See the Next Total Eclipse of the Moon?
We will get our chance to see a total eclipse of the Moon on Sunday night, January 20, 2019. North America will be turned directly toward the Moon during that eclipse and it will be very high and very accessible. That will be “our” eclipse! Mark your calendars, and be sure to get a copy of the 2019 Farmers’ Almanac, which lists dates of all eclipses next year as well as other fascinating Moon lore.