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Creating a Star Dial – Telling the Time from the Stars

A Guest Blog by Chloé.

We stare up at the stars, eyes wide, I didn’t want to miss it this time! The children had shouted in glee at sighting a shooting star and I wanted to see one too.

Then a child said, “There’s the brightest star in the sky, what is it called?”

The adults awkwardly make wild assertions, then admit they know very little about the night sky… but right there in that moment that is all they want to know and all that feels relevant.

Someone opens an app, we look in awe at the zodiac images on the screen, try to link them to what we see in the sky but the distance is too great, the connection feels distorted, we close the app and the dialogue moves on. That was March 2021 I knew I wanted more knowledge to continue the conversation and engage our children to further their curiosity; I had to start learning about the night sky.

“I knew I must be able to make a clock from the North Star”

I read reference books on the stars, nothing too engaging or enlightening, but I kept reading. Then I made a realisation, one that people had known for centuries – If all stars are stationary and we are spinning, with the north star being at the axis of our ‘spinning top,’ then the stars close to the north star (circumpolar stars) must appear to be spinning around it over 24hours. I did not know how but, I knew I must be able to make a clock from the North Star with either Ursula Major or Cassiopeia.

Information I read suggested this was true but there was a problem, 4 minutes was lost every day.  I thought ‘it will just be 4 minutes out, that’s okay’, but 4 minutes a day is 2 hours a month – and that is not okay. Interestingly the 4 minutes is because we actually rotate around in 23 hours and 56 minutes but move to the east by 1degree as we orbit the sun (1 degree equals 4minutes). Making a solar day 24 hours while a sidereal day is still 23 hours 56 minutes. Since this was to be a sidereal clock the 4 minutes lost was important.

Turning star knowledge into an object that works

Amidst all my research, someone mentioned that natural navigation maybe of interest, it did not take many clicks to find Tristan’s books. I read and audio-ed The Firmament and Star chapters over and over, I wrote notes and drew diagrams. I still had to work out how the dials should fit together and what I was to do with this 4 minute loss.

“The Nocturlabe, for the most part, has been forgotten in time”

I put it down and stepped away. I started on another quest, to recreate a Poké sundial – equally challenging. By chance whilst researching sundials I saw an image of a Nocturlabe. At first, I dismissed it as an Astrolabe but it seemed simpler and the words ‘Stellar Pole’ stood out – North Star. Here it was, the instrument I had been trying to create.

How a Nocturlabe Works

  1. Align the dial to the date. The months lie anticlockwise, each day falls back 1degree so accounting for the 4minute loss.                                                                                 
  2. Hold it up straight up by the handle and look through the central hole at the North Star.
  3. Adjust the outer handle to line up with the Plough (part of Ursula Major).
  4. The pointer will show you the time.
A Nocturlabe

The Nocturlabe, for the most part, has been forgotten in time, the only ones now available are curiosity pieces, replicas of a historical instrument. It would have gone out of common use by sailors and explorers in the 18th century when it was replaced by more accurate time keeping and navigational tools.

To bring back something that has been long forgotten was exciting. If anyone paused for a second when asking what I had been up to, I saw it as a way in to explain about the new product I was re-creating. It had become so much of my life I had forgotten that very few knew that the North Star was stationary and that a clock could be created from the circumpolar stars. There was genuine interest.

Of course, there were jokey comments about how useful phones are but the deep connection that the Nocturlabe provides with the night sky was undeniable. I became confident it was a good product that would sit well with our Adventure Toys, one children and adults would engage with together furthering more discovery.

“A simple tool to interpret stars helps regain ancient knowledge and drives further curiosity”

I re-created the Nocturlabe, re-named it StarDial and made adjustments to make it user friendly for a 10 year old child. I wanted to depict the whole of the Plough, to provide a shape they may be familiar with, rather than just using the pointer stars Merak and Dubhe.

The zodiac imagery was removed, I ignorantly thought nothing of it’s relevance. It was only with further reading I realised that our interest in the stars is to fuel our knowledge in astronomy but, in times gone by people learned astronomy to fuel their knowledge of astrology. This was their priority, to understand the movement of the Heavens. I also adjusted the dial to British Summer Time at the end of March and back to Greenwich Mean Time at the end of October. I knew the right thing to do would be to ask the children (or adult) to make this hour adjustment for themselves so they were aware of the artificial time shift. But with the time change engraved on the dial it created a conversation, I liked this, so decided to keep it.

I had a prototype made, when I first held it up, looked through the central hole and aligned it to the stars I felt immense joy to be doing something our ancestors did centuries ago, it created a feeling of self-sufficiency and knowledge I would never loose. I was however puzzled why did my StarDial seemed to be an hour out. I re-looked at the ancient models, re-read Tristan’s chapter, then decided to email him. He explained that if I was referencing historical Nocturlabes then this information would have changed. I made some adjustments, re-cut and now it was correct to within 15 to 30minutes – I was happy with this level of accuracy.

It is the process of method I was interested in, accuracy is nice, but for my StarDial it was not crucial. Seeing the position of the stars relative to our movement and having a simple tool to interpret them regains ancient knowledge and thrives further curiosity. The StarDial allows us to engage & interpret the universe from right where we are standing – that is truly magical!

Words by Chloé

Co-founder & Designer of  F r e c k l e.

Learn more about StarDial and Chloé’s work:

www.frecklestudio.co.uk


You might also enjoy:

How to Forecast the Weather Using Twinkling Stars

What are Noctilucent Clouds?

How to Find Your Way Using Stars

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