A rare lunar phenomenon will be visible in the night sky on Friday night (September 16) as a lunar eclipse is combined with a harvest moon.
The final lunar eclipse of the year is due to take place, and will coincide with the harvest moon.
Here's all the information you need to watch it.
What is a lunar eclipse?
This occurs when Earth's shadow moves across the moon. This can obviously only happen when the Earth, moon and sun are all perfectly aligned.
There are two types of shadow that can be cast by the Earth: penumbral and umbral. The umbra is a central cone of darkness that tapers away from Earth, while the penumbra is much lighter and spreads out from the edges of the umbra.
Friday's eclipse is penumbral.
What is so special about this lunar eclipse?
Friday night's eclipse coincides with the harvest moon - when the moon's face is fully illuminated when viewed from earth. This will make the contrast when it is plunged into darkness by the Earth's shadow all the more spectacular.
The harvest moon and eclipse will not coincide for another eight years, so if you miss it this time you'll have to wait until 2024 for another chance.
How long will it last?
The eclipse will last three hours in total.
What time does it start?
The eclipse is expected to begin at around 5.54pm and peak at around 6.54pm. This is clearly quite early, so we will have to hope for clearer skies on Friday evening.
Where is the best place to watch?
In the UK, we will (hopefully) see the eclipse as the moon rises.
You will have to get to somewhere like Russia, China or India to get the best view of the eclipse in the dark, however – while people living in New Zealand and the Pacific Islands will see the eclipse at moon set.
The eclipse will not be visible from North or South America. Bad luck.
What to look for
Given that this is a penumbral lunar eclipse, the changes in the moon are quite subtle.
If the sky is clear, we should see faint shadows in the upper quarter of the moon's face with the naked eye. You can use binoculars or telescopes to see these shadows in more detail.
Can I watch it on the internet?
If the skies remain cloudy, then fear not! You can still enjoy the eclipse on an online live stream on thanks to the Slooh Observatory here .