Total Lunar Eclipse 2018: What a Blood Moon Is—and Isn't

Separating Fact from Fiction

Jul 26, 2018
Lunar Eclipse

Total lunar eclipse

NASA

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The longest total lunar eclipse of the 21st century is this Friday, July 27, 2018. Some folks are calling it a “Blood Moon.” There’s boatloads of celestial hype—but also some truly amazing spectacles unfolding this summer. We’ll help you separate fact from fiction.

Total Lunar Eclipse on July 27

First, there’s that “historic lunar eclipse.” 

The truth: It might not be there at all. It depends on where you live. No eclipse will appear for anyone in the entire Western Hemisphere. In fact, none of our readers in North America will see even a partial eclipse. For those in the US and Canada, it will be a zero.

However, if you live in Asia, the Indian Ocean, Africa, Europe, New Zealand, the Middle East, and some parts of South America, you will indeed have a view. Totality will last an impressive 1 hour and 43 minutes and the entire celestial event will last nearly 4 hours.

If you’d like to check out Eclipse Night, there will be plenty of webcasts! Here are two shows that start at at 2:30 P.M. EDT.  

Bareket Observatory in Israel

Virtual Telescope Project in Rome

What is a Blood Moon?

We’ve heard all kind of strange theories about a “Blood Moon.” Back in 2014–2015, there was a series of four consecutive total lunar eclipses (Blood Moons) and the media hyped end-of-the-world prophesies. Clearly, the world did not end.

“Blood Moon” is not a term used in astronomy. It’s more of a popular phrase, perhaps because it sounds so dramatic.

It simply refers to a “total lunar eclipse.” Yep, that’s it. 

During a lunar eclipse, the Earth is passing between the Sun and the Moon, blocking the Sun’s rays. However, the Moon isn’t completely dark. What we see from Earth is the Moon slowly darkening and changing color over a few hours to an orange-red.

lunar_eclipse_sideview_full_width.jpg
Image: NASA

While most of the sunlight is indeed blocked, some rays bent around the edge of Earth and reach the Moon’s surface. Earth’s atmosphere scatters the blue/green colors (short wavelengths), but the orange/red colors (long wavelengths) reach our eyes. It’s similar to a sunset. 

So, don’t let the term “Blood Moon” throw you. Also, a fully-eclipsed Moon (the entire US and Canada will see one on January 20-21, 2019) becomes orange or coppery like a penny, not red like blood.

See our full July Moon Guide for Moon phase dates, times, facts, and folklore.

Mars Reaches Opposition!

But hold on. Here’s a dazzling sight! The very same night of this total lunar eclipse, the full Moon floats right next to Mars! Mars will be closer to Earth than it has been since 2003, shining at its brightest in the night sky.

And there’s its companion, the full Moon, guiding everyone’s eyes to it. So, you bet we want to look at the Moon that night!

Mars is so bright that it’s even outshining Jupiter. Only the Moon and Venus will shine brighter. Look for the Red Planet rising in the east around sunset below the full Moon. The planet will reach its highest point in the sky at midnight, and set in the west near sunrise.

See ”Mars at Opposition 2018: The Red Planet Approaches.”

mars-opposition-nasa.jpg
Image: Artist rendition of Mars opposition. Credit: NASA

More About Eclipses

Lunar eclipses shouldn’t be confused with solar eclipses. Both involve the Moon, but are different events.

A total solar eclipse is the greatest celestial event the human eye can behold. It’s when the Moon passes between the Sun and the Earth, blocking out the Sun for a short period of time. See the next total solar eclipse date.

An animated aurora borealis might hold second place. An exploding meteor, called a bolide, or a brilliant colorful one called a fireball might hold third place. And a brilliant comet like Hale-Bopp that came around 20 years ago might be the fourth greatest spectacle.

A lunar eclipse is interesting, but it doesn’t quite have that make-you-gasp, pedal-to-the-metal glory.

Moreover, the thrill is the solar totality. That’s when flames (“prominences”) shoot off the sun’s edge, and its corona leaps far across the sky, and stars come out, and many people weep. A partial solar eclipse, which requires eye protection, offers none of those things. That’s why “total” is the critical eclipse adjective.

But lunar eclipses are different. When the Moon is 99% eclipsed it’s quite fascinating. Nothing extra happens when the Moon plunges into the final one percent of Earth’s shadow. In fact, some might argue that 99% is more visually spectacular because there’s then one final spot of white on the Moon’s edge, which makes its overall coppery color more dramatic. Bottom line: Totality is far less critical when it comes to lunar eclipses.

Artificial Lights and Telescopes

Then there’s the question of sheer visual impact. A meteor shower can be breathtaking if there’s a meteor-a-minute, which is what will happen this summer on August 11-13. But you’ll only see 1/10th that many if you’re observing from a big city, and the sky is bright because of artificial lights.

Then, to appear glorious, there’s the issue of what equipment you’re using. Naked eye? Binoculars? A backyard telescope? It can make all the difference. A meteor shower demands you use only your naked eye. But the Milky Way and the Pleiades star cluster is best through binoculars. Yet neither of those will show a thing if you’re gazing at Saturn. That gorgeous ringed world, which hovers to the right of brilliant orange Mars all this summer, requires a 100x telescope. Binoculars are of no help there.

Through a small telescope using 100x, Mars now appears larger than the Full Moon looks to the naked eye! That’s big enough to show dusky surface markings on nights when the air is steady. (You’ll know because the stars won’t be twinkling). But when we offered that same description during the great 2003 Mars close approach, some Web writers omitted the “through a 100x magnification telescope” part. Every summer since then, some Web sites have advised looking up to see “Mars, looking bigger than the Moon!”

You’ll probably read that again this summer. But now you won’t fall for that hype, just like you won’t wonder why you won’t see a Blood Moon on July 27. 

However, this summer offers an unusually rich parade of wonderful sky spectacles. Here’s another one: the best meteor shower of 2018 peaks the night of August 12–13! Read more about the Perseid Meteor Shower.

About This Blog

Welcome to “This Week’s Amazing Sky,” the Almanac’s blog on stargazing and astronomy. Bob Berman, longtime and famous astronomer for The Old Farmer’s Almanac, will help bring alive the wonders of our universe. From the beautiful stars and planets to magical auroras and eclipses, he covers everything under the Sun (and Moon)! Bob, the world’s mostly widely read astronomer, also has a new weekly podcast, Astounding Universe

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Lunar Eclipse- 27th July 2018

Hi, I'm from South Africa and had the opportunity of viewing the lunar eclipse occurring. It was quite amazing to see it first cover up with the Earth's Shadow it seemed since it darkened slowly and then after a while turned orange.

Eclipse

We’re happy to hear that you got to see it! It must have been quite a sight to see in person. 

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