Kernow Astronomers, a club for stargazers in Cornwall, are hosting a special public viewing event of the eclipse tonight on the coast.

Frank Johns, a member of Kernow Astronomers, told BBC Radio 5 Live the eclipse "will take place very slowly".

"The description I would use is that it progresses about the same speed as the minute hand goes around, so it's not something that is instantaneous, especially here," he said.

Johns explained that the actual darkening of the moon won't occur "until it gets more than 50% covered, because the sun is very very bright".

After that there will be "a very slow eating away of the sun until it's more like a thin crisp moon", he added.

Image source, Getty Images

Ben Hatton
Live reporter

Image source, Ryan Milligan

Ryan Milligan is travelling from Northern Ireland, where about 93% of the Sun will be blocked out, to northern Spain, where the Sun will be completely hidden behind the Moon, so he can experience the moment of totality.

I ask him if those few extra percentage points of eclipse cover worth the trip - but he doesn’t even let me get to the end of the question.

"Yes, 100%" he says.

An eclipse chaser, Milligan has travelled the world to experience that fleeting moment - including trips to Chile, China, Indonesia and Australia.

"Getting into the path of totality is always the challenge," he says.

"That path, which is essentially the Moon's shadow being cast onto the Earth, is usually about 100 miles wide. So you need to get to wherever that is on the Earth. It will only be there for a matter of moments usually."

He describes the moment of totality as "a real physical experience because the temperature drops, the light becomes all weird, and your brain is trying to process all this new information".

Milligan adds: "It does become highly addictive because it is such a unique experience that cannot be replicated by any other event in nature in my experience."

Darren Bett
BBC weather presenter

The total eclipse will track from western Iceland across the Atlantic to Spain, and a little bit of Portugal.

Iceland is likely to stay cloudy with the best of any breaks in the northwest of the country.

For Spain and Portugal the picture is very different.

Here there will be little or no cloud and viewing should be excellent.

So ideally find somewhere with a clear, unobstructed view to the west – somewhere high up and away from trees and buildings.

Matt Taylor
BBC Weather

The UK is stuck in the middle of two different weather systems.

High pressure lies across much of continental Europe with low pressure and weather fronts out towards the north of the Atlantic.This means contrasting fortunes.

High pressure is expected to bring generally dry and settled conditions across much of the UK, with a hot and sunny day forecast for most.

That means clear skies should give many a good view of the eclipse.

However, across some parts of north Wales, northern England and especially Scotland and Northern Ireland, areas of cloud could push their way through between 18:00 and 19:00 BST.

Across some parts of western Scotland and in towards the north and west of Northern Ireland, we see cloud bring some outbreaks of rain.

Maia Davies
Live reporter

Image source, Getty Images

While eclipse glasses are one of the best ways to view an eclipse safely, many here in the UK have been struggling to get hold of a pair at the last minute.

Experts have urged eclipse enthusiasts not to look directly at the Sun or use their everyday sunglasses - with even brief exposure causing lasting damage - and seek out specialist spectacles instead.

But with online supplies all but sold out, they have been turning up for sale in unexpected places as retailers try to cash in on demand.

"I've sold, like, 100 this morning," a staff member at a central London bakery told the BBC on Monday.

"People have been struggling to find them all over," said a customer waiting in line for her supplies.

The scramble has prompted eclipse chasers to trawl social media for tips, turning to WhatsApp groups, Reddit and Facebook threads dedicated to tracking down the glasses.

But experts have advised real caution when using supplies found online, warning that major eclipses can attract ineffective knock-offs - the use of which could lead to serious injury.

• Read more: Eclipse chasers scramble for glasses as stocks run low

Image source, Reuters

Looking directly at the Sun can severely damage your eyes - even during an eclipse.

Even using standard sunglasses could leave you with permanently damaged eyes, so you should only look with special eclipse glasses.

The only time you can look without special glasses is for the brief period when the Sun is totally eclipsed by the Moon - which won't happen in the UK.

And you cannot use binoculars or telescopes or the viewfinder of a camera even while wearing eclipse glasses - the magnifying effect can nullify the protection of the glasses and damage your sight.

No solar glasses or handheld solar viewers? You can use an indirect viewing method, such as a pinhole camera, which doesn't involve looking straight at the Sun.

You can make a simple one with a single sheet of card or something more ambitious using a cardboard box - or you can use a colander to project multiple images on to a surface all at once.

Depending on where you are in the UK, the eclipse will be at its maximum between 19:02 BST and 19:16 BST.

What time the peak occurs for you will depend mostly on how far north you are. In general, the further north, the earlier you will see the maximum eclipse.

And, in general, the further west you are, more of the Sun will be covered.

The best places to view the eclipse are from higher ground, or areas with a clear view towards the western horizon.

Image source, EPA

The solar eclipse will first be visible in the far north of Russia, before its path slowly moves across the globe - stretching as far as northern Africa.

A total eclipse will only be visible in a few places, including:

• Reykjavik, Iceland - 17:48 local time (18:48 BST)
• León, Spain - 20:28 local time (19:28 BST)
• Zaragoza, Spain - 20:29 local time (19:29 BST)
• Valencia, Spain - 20:32 local time (19:32 BST)

Nasa has forecast that viewers in the US and southern Canada will only see a "small bite" taken out of the sun as it appears to only be clipped by the Moon - but those watching closer to its path across Europe will see most of the Sun covered up.

Here in the UK, large parts of the country will be able to see almost 90% coverage - peaking between 19:02 BST to 19:16 BST, depending on your location. More on that in our next post.

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Alex Smith
Live editor

Image source, Getty Images

Later today, people across the northern hemisphere will crane their necks towards the sky to view a celestial phenomenon.

A total solar eclipse will be visible in parts of Iceland, Spain and the far north of Russia. It is the first time such a sight will be visible from continental Europe since 1999.

A partial solar eclipse will be visible in other areas, with the UK set to experience its most dramatic event of this kind in 27 years, set to begin shortly after 18:00 BST.

Large parts of the country will be able to see the Moon cover more than 90% of the Sun - that's weather permitting, of course.

The eclipse's path will start in Siberia in Russia, travelling to Alaska in the US around 07:30 local time (16:30 BST). It will sweep round to Greenland, past Iceland and through western Europe.

We'll be hearing from people across the northern hemisphere throughout the day as they settle in to witness the phenomenon.

Get in touch to share your experiences and pictures of this rare event.