Lunar eclipses

The 21st century’s longest totality

At 1 hour 38 minutes, July’s Total Lunar Eclipse will provide the longest totality of your lifetime. But will you be able to see it?

If you’re in North America, you’re out of luck, but the rest of the world is preparing not only for a total lunar eclipse, but one with the longest duration of totality in the 21st century.

On  27 July, 2018, a Total Lunar Eclipse lasting three hours, 26 minutes and 56 seconds will be visible from the U.K., Europe, Africa and Asia.

During the totality phase, the moon will turn a rusty, brown or orange colour, and for a whopping 1 hour and 38 minutes.

Why so long? 

The moon will be travelling through the Earth’s central shadow,  and will do so at a time when it’s as far from Earth as it ever gets – a micromoon, if you will.

A Total Lunar Eclipse occurs because the Earth is between the Sun and Moon, which can only happen at Full Moon. The spectacle of a Total Lunar Eclipse begins with what’s called a penumbral eclipse, as the Moon crosses into the Earth’s lighter shadow. It loses its usual Full Moon brightness (this is the best time ever to take a photo of the Full Moon).

As it begins to enter the dark umbral shadow of Earth, one edge of the Moon begins to look pinky-orangey-brown, though not until the dark shadow has spread right across the lunar surface will it turn completely colorful. Once it has, that’s Totality, where Sunlight is being bent through the Earth’s atmosphere and on to the Moon. That’s why a totally eclipsed Moon looks like a sunset – the physics is the same.

After totality, the process reverses, with the orange colour receding as the Moon exits the Earth’s umbra. The spectacle of a Total Lunar Eclipse also very easy on the eyes; no special glasses are needed to view it safely, and you don’t have to travel because a lunar eclipse of some kind will be visible from where you live every couple years or so.

From the UK, only totality and the second partial phase will be visible. The moon will rise above the eastern horizon at 20:49, when it will already be in the totality phase. The sun will set at 20:56 p.m. (in London), and by 21:21 p.m. the moon will be at its maximum eclipse, though it won’t stop being blood red until about 22:13 p.m, when totality will cease. UK observers will then see a partially eclipsed moon until 23:19 pm, when the full moon will gradually return to its regular brightness as it exits the Earth’s shadow.

A totally eclipsed moon-rise? It’s sure to be a special sight indeed.

Image credit: CC0 Creative Commons