On Friday 27th July 2018 you will have a chance to see a total lunar eclipse from the UK. There will be 85 total lunar eclipses this century, and when you take into account the weather and the fact that some of the 85 won’t be visible from the UK, this makes them pretty special events.
How to See it
Look South East after Sunset, no binoculars or telescopes will be required. Local times will vary but for the South West of England the Moon will rise fully eclipsed at 9pm having been fully eclipsed since 8:30pm. So although this will be the longest eclipse of the century with totality lasting 1 hour and 44 minutes, we will have missed half an hour of it by the time the Moon rises above the horizon.
This eclipse happens to be occurring when the Moon in farthest away from Earth in its orbit, that’s why you may see it described as a ‘Micro’ on ‘Mini’ Moon eclipse. The Moon being as far from the Earth as it can get is also why this is the longest eclipse of the century.
You may initially find the Moon tricky to spot as there will still be a lot of twilight around with the Sun not even having set at the time the Moon rises. As twilight fades away and the Moon climbs up in the sky it will get increasingly easy to see.
Bonus thing to look out for – on the same evening as the lunar eclipse, Mars happens to be at opposition i.e. its brightest. Mars will rise at around 9:40pm and will be visible below the still fully eclipsed Moon. Mars will be unmistakable – very bright and very red.
If the weather is cloudy, the next opportunity to see a total lunar eclipse will be Monday 21st of January 2019, so not too long to wait although viewing it will involve getting up at 5am!
6:16pm – partial eclipse begins, the Moon is beginning to entering the penumbra. This is happening below the horizon for the UK.
7:25pm – Total phase begins to advance across the Moon as it enters the Earth’s penumbral shadow, the Moon is still below the horizon for the UK
8.30pm – Moon is now fully eclipsed, completely in Earth’s umbral shadow now. Still not visible in the UK at this point.
9pm – Fully eclipsed Moon rises for viewers in the South West of England, yay!
10:15pm – Total eclipse ends, the dark red moon will start giving way to the Earth’s penumbral shadow.
11:20pm – No umbra left, it’s only the penumbra now and the penumbra will start giving way to no umbra. This is an interesting but subtle effect.
12:30am – Moon fully exits the penumbral shadow, everything is back to normal and the world didn’t end.
Why do Lunar Eclipses Happen?
The Earth casts two shadows into space: umbra and penumbra. When the Moon enters these shadows, a lunar eclipse occurs. A total lunar eclipses happens when the Moon passes into the umbra. At this point, the only light reaching the Moon has been refracted through Earth’s atmosphere. Due to a process called Rayleigh scattering, red light travels through Earth’s atmosphere without being affected as much as other colours of the spectrum. The red light then travels onto the Moon making it appear red, hence why you’ll hear total lunar eclipses referred to as ‘blood moons’.
Lunar Eclipse Tips
Go somewhere with a good South East/South view.
If the weather is not looking great for your location, consider travelling to somewhere with a better forecast.
After the dramatic blood red total eclipse stage is finished, there will still be a partial lunar eclipse happening until around 12:30am. This is much more of a subtle affair, but it is still interesting to see. Some people report that the Moon looks a bit ‘tea stained’, and photographs can reveal how the partial phase of the eclipse is progressing. This was a shot from a penumbral lunar eclipse last year