Get ready for the partial eclipse

There will be a partial eclipse of the Sun visible from the whole of the UK on the morning of Tuesday, 25 October 2022. But while it’s easy to view it safely, you need to be prepared in advance, so get your act together now!

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Partial eclipse of the Sun. Photo: Robin Scagell

 

What, where and when

A partial eclipse occurs when the Moon is new and happens to pass directly between the Earth and the Sun, so you see it silhouetted against the Sun’s disc. This doesn’t happen every new Moon, and even when it does, you need to be in the right part of the Earth to see it. In this case, only those in most of Europe, North Africa and the Near East will see it.

The eclipse will be visible from the whole of the UK, weather permitting of course, although those in the north of the country will see more of the Sun covered than those in the south. The appearance of the Sun at maximum eclipse and the times of the start, middle and end are shown on the map below.

Because only about a sixth of the disc of the Sun is covered the sky won’t go dark, and even if it is sunny you probably wouldn’t notice anything unless you were aware of it, unless you glimpse the Sun through cloud. Imagine the alarm of people in ancient times who happened to glance up and saw the Sun progressively being eaten!

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How the eclipse will look, and timings. Image credit Society for Popular Astronomy

How to watch the eclipse

You need to take great care when viewing the Sun at any time. It’s so bright that you need to dim its light by about 100,000 times before you can gaze at it safely. So read our FAQs below to find out what your options are. If you need to buy suitable filters or glasses, don’t leave it so late that you can’t get them delivered – they aren’t available from any regular shops!

We’ve recorded a five-minute video with our Vice President and Chief Stargazer Prof Lucie Green in which she shows you how to view the eclipse safely using nothing more than a small mirror! There’s also advice on how to buy and use special eclipse filters.  Watch it now!

Eclipse FAQs

How can I view it?
The Sun is so bright that looking at it directly will blind you. Even at mid eclipse, the remaining bright part of the Sun is far too bright to view. You need to cut its brightness down by about 100,000 times. Ordinary sunglasses are useless, and you should never use household materials such as bin liners, food wrappers or the like (see below). So either use an authorised eclipse viewer, or project the Sun’s image using a small mirror or a telescope or binoculars. A welder’s No 14 glass is also OK for viewing directly.

Where can I get an eclipse viewer or material from?
Only specialist astronomy suppliers may have stocks. The most commonly used material for making filters is Baader AstroSolar, available from a number of suppliers, but other materials are available.  Just search for ‘solar eclipse viewer’ or ‘Baader Astrosolar’.

I’ve often had to look into a low sun when driving – what’s the problem?
Under those circumstances your eye will not fix on the Sun itself but will dart around and a reflex action prevents you from gazing at the actual Sun. But when trying to see the eclipse you may try to force yourself to overcome this reflex, which is dangerous.

Can I view it through thin cloud?
Quite often we do see the Sun’s disc through cloud with no problems. The problem is that when viewing an eclipse we tend to stare at it for longer than we would usually do so, which could cause a buildup of heat. This must be your own decision – if the Sun is so much dimmed by cloud that it’s hardly brighter than the cloud itself, it may be OK for you to look at it briefly, but eyesight sensitivity varies from person to person and this is not based on medical advice. Look away the instant that the cloud thins.

What about looking at a reflection in water?
This cuts the brightness down to only about a few per cent of the original brightness – not nearly enough for safety, no matter how dirty the water!

Why can’t I look through a photographic negative like I did when I was young?
Years ago, most photos were taken on black and white film, and the black areas of the negatives were made of silver particles. A couple of layers of these could cut down all wavelengths of light quite well. But colour negatives use dyes rather than silver, and these don’t absorb all wavelengths of light equally. The worst thing is that even though they cut down the visible light, so the Sun looks dim, they may allow through other wavelengths, such as infrared (heat) which will quietly fry your eyeball without your realising it until it’s too late. The same applies to many other dense materials, such as bin liners, smoked glass, food packaging and CDs. So don’t take the risk!

Where will the eclipse be total?
It won’t. On this occasion the central part of the Moon’s shadow, where a total eclipse takes place, misses the Earth completely. The maximum amount that the Moon covers the Sun from anywhere on Earth is from Siberia where the Sun will be about 85% obscured.