The longest blood moon of the 21st century is going to take place this month, giving stargazers and the general public alike the chance to see something pretty special.

For almost 2 hours on the 27th July, stargazers will be able to watch the Moon turn the colour of blood red in a phenomenon that usually takes place once every few years.

What is a blood moon?

A blood moon is essentially another word for a total lunar eclipse. This happens when the Earth passes between the Sun and the Moon.

During complete totality (the moment when the Earth is completely obscuring the light from the Sun) the Moon will turn a deep orange colour.

The reason for this is that the only light reaching the Moon will have been passed through the Earth’s atmosphere. The Earth’s atmospheric composition will then greatly determine just how blood-coloured the Moon becomes.

wWhat you’ll see during the whole phase of the lunar eclipse will be the Moon steadily getting darker and darker before it quickly turns a dark red colour.

Once it passes back out of the Earth’s shadow it’ll then switch back to being its normal colour and steadily increase in brightness again.

If you’re curious about what causes this, NASA has a really helpful video here:

When is the blood moon?

In the UK, the blood moon will take place on the night of Friday the 27th July 2018.

It’s believed that the phenomenon will start at 8:49 pm and will carry on for around an hour and 23 minutes depending on how east you are in the UK.

Those in East Anglia and on the east coast will have the best chance of seeing it for longest, while those in the west will still see it, but it’ll pass quicker.

If you’re in Europe then it’s likely you’ll have the best view, while those in America sadly won’t see the phenomenon at all.

If you miss this one don’t panic as there’ll be another long blood moon in around 80 years. Don’t say we didn’t warn you.