Monday, September 25, 2023

Transit of Mercury: A Good Day for Solar Observation in Belper

Belper Transition and the Big Energy Project had a successful viewing of the transit of Mercury on Monday the 9th of May.

It was a marvellous day with a clear sky and good viewing conditions. Visitors arrived throughout the day and were able to see Mercury crossing the face of the Sun, which we had successfully projected onto a makeshift screen. Visitors were also given the opportunity to view the transit through a solar filter. An “easy to point” solar projection box was also to hand and this gave reasonable views of the transit – as promised by the makers of the box, Astro Media.

It was good to see so many people interested in the event. As reported in previous articles in Nailed the transit needed a relatively high magnification to be seen at all, and the most frequent comment we received from visitors was  “thanks, I would not have seen it otherwise”.

We set up in the Strutts garden at around 11.30am. We had a kelly kettle boiling up water for a brew and by 12 noon the telescope and projection box had been positioned to produce a good sized solar disc.


The image of the Sun was sharp and we could clearly see the, now familiar, sunspot (No.2542). At 12.05 we were joined by two visitors eager to see first contact at 12.12. The moment arrived. We leaned in to get a better look, but at 12.13 there was nothing to see. This was a tense moment for us, we knew that our target was small and there was a possibility that our telescope would not be powerful enough to see Mercury clearly. One of our visitors looked at their watch “it’s nearly 12.14 now”… and then, just after 12.14, we could see a small, black dot close to the inner rim of the Sun. We had a sighting!

For the next four and half hours we were joined by a succession of visitors interested in    watching the stately progress of Mercury as it moved across the face of the Sun.  In the picture below Mercury is the small dot at the 7 o’clock position. The other dot is the sunspot No. 2542.


We sometimes watched with a yellow filter on the lens – which gave the Sun a more natural look, but our best results seemed to be with a red filter, which heightened the contrast between Mercury and the Sun. As we were situated in the garden at the Strutts Community Centre we were also able to relax, drink cups of refreshing red bush tea, appreciate the sunshine, listen to the birdsong, spot frogs leaping into the pond at the back of the garden and generally enjoy our surroundings.

Viewing was good throughout the day and we observed about three quarters of the Transit, packing up at around 4.45pm.

For more details about the day and pictures of the event you can also visit:

By Tony Webster

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