A partial eclipse of the Sun
On March 14th there will be an eclipse of the Moon.
Then, a fortnight later, comes a partial eclipse of the Sun.
It’s coming to our sky on Saturday March 29th.
Sadly this will not be a magical total eclipse.
In the UK we’ll have to wait until the year 2090 to witness that event.
If it’s cloudy then, the next one is in 2133, followed by another in 2135.
I don’t think I’ll be there for any of these!
So for now we’ll make do with the event this month.
Times
The eclipse will happen on the morning of March 29th
It will begin at around 10am and end at noon.
The times are slightly different, depending where you live.
Here are some example timings:
London: 10.07 to 12.00
Birmingham: 10.05 to 12.03
Glasgow: 10.07 to 12.06
So the maximum eclipse will be around 11am wherever you are.
Eclipse Appearance
The partial eclipse will see the Moon cover around one-third of the Sun’s disc.
In a total eclipse, the Sun neatly covers the whole of the Sun.
That is one of nature’s wonders.
The sky goes dark, stars and planets appear in the day.
It’s a spectacular, mystical event.
A partial eclipse is not so amazing.
In fact, if you didn’t know it was happening, you wouldn’t notice it.
The Sun’s radiance will be unaffected.
It remains full daylight.
Partial Eclipse of the Sun
The Astronomy
An eclipse of the Sun happens when, from our viewpoint, the Moon moves in front of the Sun.
The Moon casts a shadow on a small part of the Earth.
Inside that shadow, the Moon covers the disc of the Sun.
Or, as on March 29th, it covers part of the Sun.
From the UK, about one-third of the Sun will be covered at maximum eclipse.
Warning!
Solar eclipses come with a safety warning.
Do NOT look at the Sun directly.
Doing so can permanently damage your eyesight.
Once I projected the Sun’s image through binoculars.
I accidentally left the cover off the objective lens.
Within a few seconds the eyepiece cover was smoking!
The Sun’s heat had burned a hole in the plastic.
That’s why we say that looking directly at the Sun can permanently damage your eyes.
Eclipse Specs
You can safely view the eclipse with special eclipse spectacles.
The filter takes out almost all the sunlight – and importantly, all of the heat.
If you have some eclipse specs, please check them before use.
Even tiny holes or defects can cause problems.
Photo: Dennis Ashton
Projection
Projecting the Sun’s image onto a screen is the safest way to view the eclipse.
Then the image can be viewed by several people at the same time.
Projection: Pinhole Camera
The simplest projection method is a pinhole camera.
Pinhole projection: NASA
I used a piece of card and cut a hole in the middle about 3 cm square.
Then I stuck a piece of kitchen foil over that hole.
Finally, I made the pinhole in the foil.
That makes a much neater hole than trying to make one directly in the card.
The image is small but clear.
The larger the distance between hole and screen, the bigger the image.
Pinhole projection: NASA
NASA’s site has instructions for the pinhole projector.
Projection: Binoculars
Another safe way to view the eclipse is to project the Sun’s image using binoculars.
It gives a much larger image of the Sun’s disc.
Close off one of the lenses then aim the binoculars at the Sun.
The Sun’s image will project through the instrument.
You can project the Sun’s image on to a piece of white card.
Then you can photograph the projected image.
You will have to nudge the binoculars to follow the Sun during the eclipse.
Projection: Flat mirror
This is a remarkably easy way to view the eclipse.
It works well for a group of people to view the eclipse together.
I tried it out some time ago to safely observe the Sun.
You need a flat mirror, like a handbag or bathroom mirror.
Cover the mirror, leaving a small hole at the centre.
I used a bathroom mirror on a swivel base.
To create the small reflecting area, I covered the mirror with gaffer tape.
The mirror can be used to reflect the Sun’s image on to a white card screen.
The screen should be in the shade.
The only problem is that you need a long distance between the mirror and screen.
The distance must be several metres to generate a sizable image of the Sun.
Mirror and screen about 8 metres apart.
Image of the Sun: Dennis Ashton
As you can see from the photos, this simple projection worked really well.
It’s a lovely way to see the eclipse on 29th March.
Prof’s magic mirror
In 1996, another partial eclipse was visible in the UK.
Then I worked at Star Centre at Sheffield Hallam University.
We decided to put on a public observing event.
So we set up expensive telescopes with solar filters in the middle of Sheffield.
Lots of shoppers saw the eclipse through our instruments.
Dennis with Star Centre astronomers: D. Ashton
But the highlight of the morning was Prof’s magic mirror.
Professor John Parkinson of Hallam University came along.
He brought no expensive equipment.
Instead, he took out of his pocket a small handbag mirror.
He set it up in a small stand and projected the Sun’s image on to our white Central Library wall.
Everyone passing through the town square could look up and see the eclipse.
It was brilliant!
If you would like to show the eclipse to a group of people, it’s the best way.
To see more, the British Astronomical Association has instructions.
Credit – RAS/Lucinda Offer
Good Luck!
I hope that your sky is clear on March 29th so that you can observe the eclipse.
Please use one of our safe methods to view the event without damaging your eyes.
The author: Dennis Ashton is a Fellow of the Royal Astronomical Society and a Wonderdome presenter.
In 2024, Dennis received the Special Contribution award from the British Association of Planetaria.
Wonderdome now has 14 presenters, making us the largest – and best – mobile planetarium organisation in the UK.
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