By Jamie Carter
July 24, 2018
Lunar Eclipse with Blood Moon
Credit: Franco Emmanuel Remo Romero/Getty Images

The longest total lunar eclipse of the 21st century happens on July 27, but North America will miss it. Thursday night's full moon – known as the buck moon – will pass right through the center of the Earth's dark shadow in space, just as it did during January’s super blue blood moon eclipse. As it does so, the only light that reaches its surface will be sunlight that has traveled through the Earth’s atmosphere. That will turn the surface of the moon into an orange, copper red color for one hour and 43 minutes.

Sadly this spectacle won't be visible from North America, where it will be daytime; it will only be visible on the night side of the planet. However, the totally eclipsed moon won't be the only red object in the night sky that night as the planet Mars reaches the brightest it's been in 15 years.

What is syzygy?

When the sun, Earth, and moon all align with each other, astronomers call it "syzygy." This happens during all eclipses, both total solar eclipses and total lunar eclipses. However, on July 27, there will be a special kind of syzygy because not only will our planet get precisely between the sun and the moon, but also the planet Mars.

Since Mars takes almost twice as long as Earth to orbit the sun, it forms a straight line with the Earth and sun every couple of years. Astronomers call this "opposition." Planets look brighter when they are at opposition because they're directly behind Earth and in full glare of the sun, so from our perspective on Earth, their entire disk is lit.

How to see Mars in 2018

Although North America won’t get a view of a totally eclipsed moon, it will be possible to see a full moon with a very bright Mars just below it. That’s because Mars will be closer to Earth than at any time since 2003. It will therefore be super bright, roughly five times brighter than usual. It won't get this close again until 2035, so the next six weeks is the best time to look at the Red Planet through a small telescope.

What is a blood moon total lunar eclipse?

Despite its name, a blood moon is not exactly red. It actually looks more of an orange, copper, or pink color during totality, the period of time it spends in the darkest part of Earth's shadow. A total lunar eclipse occurs when the Earth is between the sun and moon, which can only happen during a full moon.

Since the sun is always shining on Earth, it always projects a huge Earth shadow into space. However, because the moon orbits at a slight angle, it rarely enters that shadow. When it does, it loses its brightness in one corner. That spreads until the shadow is covering the entire surface – that’s totality. During this period the moon will take on a copper, red, pink, or orange color.

Totality tends to last an hour, but on July 27 it will stretch to one hour and 43 minutes because the moon just happens to be as far from Earth as it ever gets. It’s a micro-moon, the opposite of a supermoon.

Best places to view the 2018 blood moon total lunar eclipse

The total lunar eclipse on July 27 will be visible from the U.K. and Europe, Africa and Asia. Cities on the night side of the Earth with a good view of the blood moon during totality include Tokyo, Budapest, Cairo, Sydney, Melbourne, New Delhi, Moscow, Beijing, Hong Kong, Rio de Janeiro, and Buenos Aires. Since the Delta Aquarids meteor shower will be underway, it may be possible to see shooting stars during totality.

Can I see the blood moon from the U.K.?

Yes, but only just. Although this total lunar eclipse is visible from the U.K., it's only slightly so. In fact, as the moon appears on the eastern horizon just before sunset, it will already have entered Earth's shadow, so it may look slightly pink as it rises. Observers in the U.K. should find a clear view to the horizon at 20:49 p.m. BST on July 27 to watch the event. By 21:21 p.m. BST the moon will be at its maximum eclipse amid darkness, and remain totally eclipsed until 22:13 p.m BST. At 23:19 p.m. BST, the Moon will return to its regular brightness as it exits the Earth's shadow.

When is the next blood moon total lunar eclipse?

Although North Americans don't get any joy from this total lunar eclipse, there's not long to wait for the next one. We're currently in a period of regular total lunar eclipses, with the next one observable from North America due on Jan. 20, 2019.