Why is the moon so red? Tonight's blood moon lunar eclipse explained

As soon as the moon rises from behind the horizon, it will be darker and redder than usual

Andrew Griffin
Friday 27 July 2018 11:36 EDT
Comments
Blood Moon 2018: the longest lunar eclipse of the century

Your support helps us to tell the story

From reproductive rights to climate change to Big Tech, The Independent is on the ground when the story is developing. Whether it's investigating the financials of Elon Musk's pro-Trump PAC or producing our latest documentary, 'The A Word', which shines a light on the American women fighting for reproductive rights, we know how important it is to parse out the facts from the messaging.

At such a critical moment in US history, we need reporters on the ground. Your donation allows us to keep sending journalists to speak to both sides of the story.

The Independent is trusted by Americans across the entire political spectrum. And unlike many other quality news outlets, we choose not to lock Americans out of our reporting and analysis with paywalls. We believe quality journalism should be available to everyone, paid for by those who can afford it.

Your support makes all the difference.

If you're out tonight, look up: you might catch sight of the blood moon, and some other sights besides.

Unless the rain is ruining it, the UK is preparing for a lunar eclipse, during which the moon will turn a deep, bloody red and go much darker than usual.

And this one is extra special, marking a potentially once-in-a-lifetime experience: there won't be a lunar eclipse this long this century.

But why does the moon look so strange and red? It's all about light and location.

Why does it happen?

A eclipse happens when the Earth, Sun and Moon get in a line. In a lunar one, the Earth is in the middle – it sits between the Moon and the Sun and stops light getting between them.

The bloodiness comes as what light does get to the Moon makes its way around the Earth. As it does so, it is scattered, so that the longer wavelengths make it past the Earth and so are a deeper red.

It also means that the moon is much darker, because less light is getting to it.

When will it happen?

When the moon rises over the UK – at about 9pm – the lunar eclipse should be visible. But you might want to wait another hour or so until the sun has fully set and the sky is darker, which will allow you to see more of the dim disc of the moon.

Why is it called a 'blood moon'?

Because it's red, and looks faintly gory. There's nothing more to it than that.

But the name does appear to have encouraged the kinds of people – mostly British newspapers and YouTubers who identify themselves as pastors – who like to trick others into believing that there is something sinister or dangerous about the lunar eclipse. For that reason, some suggest the name should be dropped.

Join our commenting forum

Join thought-provoking conversations, follow other Independent readers and see their replies

Comments

Thank you for registering

Please refresh the page or navigate to another page on the site to be automatically logged inPlease refresh your browser to be logged in