Tag: History of astronomy

Measure to the Moon 2020 – a reflection

On By cornishstargazerIn History of astronomyLeave a comment

Back in 2020 Mayes Creative ran a bit of a bonkers project where I asked you all to take photographs of Venus and the Moon wherever you were in the world. We had lots of people take part and loved how enthusiastic everyone was about joining in. One of these was the late eminent astronomer Jay Passachoff who had written about the method that could be used to measure the distance from Earth to the Moon.

I had been fortunate to meet Jay and hear all about his travels to see solar eclipses at a Society for the History of Astronomy Conference in 2018 and have been saddened to hear of his passing this week. He was always very encouraging of grassroots astronomy.

So I feel blessed to have had his support with this fun socially interactive project. Here is how what we did to measure the distance to the moon and the results we obtained.

The idea was to re-enact the historical ‘Transit of Venus’ which astronomers travelled around the world in order to measure the distance to the Sun using parallax. We attempted the same thing but with the Moon and Venus using social media with people sending their images back to us digitally. Once all the images of the Moon and Venus were received we worked out how to get a distance to the Moon using similar historical techniques. This was done by photographing the position of the crescent of the Moon in relation to Venus, as this would change depending on where you were positioned on the Earth. Over the past 3 months, we had great responses from around the world which enabled us to measure the Moon’s distance. 

We wanted to report back on how close a result we got from our ‘Measure to the Moon’ parallax project. 

February – the first event/ trial run.

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We had a good response but mainly from the UK, the furthest image we had to use as a baseline for the Parallax was from Portugal, we saw this as a trial run. The resulting distance we calculated was 271,734km and the Moon was 360,461km away from Earth, so we were a whopping 24.6% out.

March – the second event.

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We had many images for the March attempt, including some from the Abu Dhabi Observatory and also the Philippines which really helped us get a better idea of the parallax shift. This resulted in a calculated distance of 340,014km, the Moon at that time was 357,122km away so just a 5.03% difference, which we thought was pretty amazing. 

April – the third/last event.

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The final attempt in April was marred by clouds here in the UK, although there were clear skies in the South-West. We did have a number of US observers taking part including members of Flagstaff and Jay Pasachoff in New York – making the project international. We got a resulting distance of 315,736km, the Moon at this date was 356,906km away, so we had a difference of 11.5% – pretty respectable.

So overall the March attempt had the closest result due to the number of photos we received from all over the world. There were lots of lessons learnt along the way, but we were pretty pleased with the results. We really enjoyed this and may run something similar in the Autumn involving Mars. 

We followed Ernie Wright’s methodology to make the measurements: http://www.etwright.org/astro/moonpar.html 

A Mayes Creative intern wrote a short computer program which scale-plated all the images and came up with averages. Then made all the calculations with guidance from astronomer Carolyn Kennett.  

If you have enjoyed this maybe you would like to check out the following which eminent astronomer Jay Pasachoff shared with Mayes Creative.

Pasachoff, Jay. M., Gährken Bernd., and Schneider, Glenn., (2017), “Using the 2016 transit of Mercury to find the distance to the Sun,” The Physics Teacher 55, 3 (March), 137-141: cover illustration plus article: http://doi.org/10.1119/1.4976653

Alan Stern et al., New Horizons team, from beyond Pluto: http://pluto.jhuapl.edu/News-Center/News-Article.php?page=20200417

Udo Backhaus, Germany, from the 2019 transit of Mercury: http://www.transit-of-mercury2019.de/results.php

Goodaver: Then and Now

On By cornishstargazerIn cornwall, watchingthesunLeave a comment

Please be aware Goodaver circle is on private land and permission must be sought before visiting it.

Within the digitalised Stanley Opie collection of photographs in Penzance’s Morrab Library, there are three images entitled “Unidentified stone circle. Possibly on Bodmin Moor”. The photos give an impression of a typical Bodmin Moor circle in the style of the Stripple Stones, situated on open moorland with extensive views. But on closer inspection, it cannot be the Stripple stones as the stones and landscape do not match details in the images.

Stanley Opie was an archaeologist who liked to take photographs of historic sites and archaeological digs in Cornwall. Born in Barncoose, Redruth in 1884 he used an Ensign Cameo No. 2 camera with Imperial Eclipse plates to take his photos between 1930–50. The collection is housed in the Morrab Library in Penzance and has been digitalised and is now accessible online and through authorised visits. During his career, he imaged many sites around Cornwall and some further afield and it must have been a huge job to try and identify some of the places in the images.

Examination of the three images shows them to be of Goodaver stone circle on Bodmin Moor. This may surprise people as a visit to the circle today is an entirely different prospect. The circle is surrounded by trees that have been grown as part of the local plantation. It gives an enticing view of how the circle may have been positioned and the possible sightlines. It allows us to postulates about astronomical alignments which may have been of importance to the original builders.

In recent times the whole site has become encircled by trees, other than a view to the west where the hillside drops to the farm and river bed below.

There was an opportunity to visit the site and image the circle before an attempt was made to match the orientation of the Opie photos and the landscape features within. It would be interesting to identify the possible sightlines from the circles if the trees were not in place, sightlines that the original builders may have had when choosing where to position their circle.

The Rabbit stone helped orientate the circle in the photos (to the left of the image

It helped that there are a number of unusually shaped stones. One in particularly got named the rabbit stone after having a similar profile of the Lindt rabbit, it can be seen on the left of this image. (I should say at this stage that the circle was heavily restored in 1906 and some of the stones are thought to have been replaced incorrectly, even upside down).

Opie Photograph no 1

This image took a bit of matching. The two central blocky looking stones and the rabbit-shaped stone on the right of the image helped orientate it. In my image below the rabbit, the stone is also to the right and slightly obscured by the rocks in front of it.

The rise in the ground beyond the circle is Brown Gelly, this is towards the southwest. This Tor is obscured by the trees in the left of the more recent image. The area has a number of interesting ancient sites on it including a number of Cairns on the top, which can be seen on the ridgeline of the image. There can be no solar or lunar alignment with these local cairns as they are too far to the south when standing within the circle.

Stanley Opie, “Unidentified stone circle. Possibly on Bodmin Moor,” Morrab Library Photographic Archive, accessed January 4, 2022, http://photoarchive.morrablibrary.org.uk/items/show/6371

Image 1 match

Opie Photograph number 2

This second image gives a more expansive view looking out from the circle to a number of ridgeways and hills beyond.

Looking at the stones in the image, the tall pointy stone and gap, next to the man at the front of the circle helped orientate the image, as did the rabbit-shaped stone behind him. The image looks from the south of the circle facing north.

The hill towards the centre-left of the image is Leskernick, it is possible that Bronn Wennili (Brown Willy) is visible to the left of the image. This is exciting as it means that standing in the circle you could have seen the summer solstice sunset over the distant hill. This is an extension of the line which starts at the newly discovered menhir on the ridge above the Hurlers circle, extends through Craddock Moor circle and the avenue at Craddock Moor, onwards to Goodaver circle. Making it possible to see the same summer solstice sunset at a number of important prehistoric locations across the moor.

Continuing to the centre-right of the image is the local plantation ridge. Fox Tor which is relatively local to the circle would have been to the right of the image.

The pointed stone which the man is stood beside in the Opie image is front left in the recent one. My image is orientated slightly differently from the old image. It would have been pointing directly down the field to the right of the modern image. Looking down the neighbouring field in recent times there is no possibility of seeing what hills lay beyond.

Stanley Opie, “Unidentified stone circle. Possibly on Bodmin Moor,” Morrab Library Photographic Archive, accessed January 4, 2022, http://photoarchive.morrablibrary.org.uk/items/show/6370

Image 2 Match 

Opie Photograph no 3

The Opie photo shows stones in profile against the sky above with no plantation beyond, the rabbit-shaped stone is in the front row of the circle on the central left. Matching it to my photos of the circle, it has been taken from the northwestern side of the circle down the ridge a little way. Kilmar Tor would have been visible if the photo had been taken with slightly increased elevation. This Tor is directly east from the circle and in the position of the rising sun at the equinox (midpoint between the solstices).  The modern photo has been taken from higher up the hill and the craggy tops of Kilmar Tor can still be seen through the gaps made by the less dense boundary of trees.

Stanley Opie, “Unidentified stone circle. Possibly on Bodmin Moor,” Morrab Library Photographic Archive, accessed January 4, 2022, http://photoarchive.morrablibrary.org.uk/items/show/6372

Image 3 Match

A plan of the matched direction of the photographs taken by Opie numbered 1-3

From matching the photographs old to modern I was able to make a plan of the directions that the Opie images were taken in: The plan below it is as follows:

R = Rabbit stone

L = taller long stone

Credit: Annotated Google maps image

Finally, I should add that within the Opie photographs none were taken in the direction of Hawks Tor in the west. This has been identified by Cheryl Straffon and John Barnett as an equinox setting position when standing in the circle. When visiting the circle in more recent times the Tor can still be seen in the gap made by the plantation to the west and is the one remaining solar alignment that could be viewed in action. Maybe one day the larger plantation trees will be replaced with smaller saplings and make the other viewpoints possible.

Access to the Stanley Opie collection and all the other wonderful historic digitalised images that the library has can be made here:

http://photoarchive.morrablibrary.org.uk/

Lighting the Darkness – Tregeseal passage grave and cross based urns

On By cornishstargazerIn UncategorizedLeave a comment


First appeared in Meyn Mamvro Issue 100, First Series, Winter 2019

https://www.meynmamvro.co.uk/archive/

Tregeseal, Scillonian Style Passage Grave


The importance of the Sun has been recognised throughout history. This luminous body defined the lives of people it shone on and the clocklike regularity of its rise and the set was well understood by humanity. Due to its significance symbolic representation of the Sun stretches far back into prehistory. Designs including the Sun weren’t uncommon and by the Bronze Age examples of solar symbolism are found across a range of mediums. Drawings and designs were often abstract in nature. Representation included circles, waves and cross shapes. The cruciform shape in particular has been linked to the Sun by Mary Cahill (2015) and her work on Irish Sun discs. These are flat circular objects made of gold, designed to shine brightly when sunlight radiates onto them. The etching of a cross on the surface shows the rays of the Sun in a conceptual way, maybe representing various solar events such as; Sundogs, pillars, rays and halos. Although no Sun discs have been found in Cornwall, these golden objects have also been linked to the lunula. A lunula was found with a pair of Sun discs in Coggalbeg, Co Roscommon, confirming an association. Furthermore designs on lunula lend themselves to observation with sunlight. There are examples of lunula found here in Cornwall and if you get the chance it is worth visiting the Penlee House Gallery where the Penwith Lunula is on display.

Sun discs with cross-shaped designs were found at Tedavnet, Co. Monaghan Ireland. Image Credit: The British Museum.


Other objects discovered in Cornwall from this period incorporate a cross design. Although perhaps not as glamorous as a golden disc, local urns can include a similar decoration. Trevisker style urns are a design of urn which are predominantly found in the South West of the UK. Dating from the Bronze Age the style is known for its hash/dash and zig-zag lines and use of local materials such as gabbroic clay from the Lizard peninsular. On occasion, the urns have a cross or cruciform design within the interior of the base. This seems to be a rare occurrence but there have been examples of cross based urns found at the Trevisker village excavation, Boleigh barrow, Tregeseal chambered tomb and an example from further afield in Kent. This final example was placed in a ring ditch, and the soot recovered from inside the Urn was radio carbon-dated to 1600-1320 cal BC. It was found shattered into over 200 pieces but was reconstructed, with its internally crossed base being clearly observable.
The urn from the Tregeseal chambered tomb was recovered by William Copeland Borlase in 1879. Found at the end of the passage, in a separate area, it was recovered almost complete by Borlase during his excavation. It now resides within the British Museum. Tregeseal Chambered tomb is part of a group of Bronze Age entrance graves in Penwith which include Bosiliack, Tregiffian and Pennance. As an aside radiocarbon dating results on a burial at Bosiliack gave 1690-1510 cal BC (Jones, A and Thomas, C. 2010) a similar date to the urn found in Kent. The Tregeseal urn is a large example and is 21 inches in height. The Cross shape was meticulously drawn in plan form at the time. The plan was reproduced in the London Illustrated Times and it can also be seen on the wall of the Penlee House Gallery Museum in Penzance.

Trevisker Urn from Tregeseal. Image Credit British Museum Collection Online.
The cross itself would not be integral to the structure of the urn. There seems to be no practical explanation as to why an urn of this size would have this addition in the base. It is therefore interesting to consider if some Trevisker urns could be following the tradition of Sun discs and offer a design that is indicative of solar symbolism? One aspect which strengthens the case of this idea is that the Urn would have started as a disc shape on which the cross shape would be added. Then the sides would have been added to the urn creating the final vessel. Looking down from the mouth of the urn it would have clearly taken on representation of the Sun in a similar way to the Sun disc design. An alternative explanation has been offered by Kavanagh, R (1973) who suggested that the cross was added to demonstrate a bottom of a basket and was a nod to the basketry traditions of the period.

The Tregeseal Urn base – in plan.
Image credit: Report by W.C Borlase circa 1879


The Tregeseal example was discovered within the tomb base up, containing cremated remains. So the cross would have been above the remains. This could have been intentional. Many funerary urns are found base up. A cross at the top could represent a number of ideas. A Sun in the dark? A route to the heavens? A set Sun? There was just one time of the year which the Sun would shine down the chamber to its rear. This was the winter solstice sunrise. A recent survey undertaken by Carolyn Kennett and Grenville Prowse supervised by Penwith Landscape Partnership archaeologist Jeanette Radcliffe found the passage to be orientated at 128degrees. This orientation towards the solar extreme of winter solstice sunrise is in common with local tombs at Bosiliack and Pennance. On this day the sunlight would shine down the passageway hitting the back upright stone at the rear. The urn was positioned behind this back stone in a separate area or cist. Although currently it is difficult to understand the full design of the tomb, as this rear section has been removed and our understanding is reliant on the original plan from the Borlase excavation. It is also worth considering if the positioning of the urn in a separate section was intentional? This position would ensure that no natural sunlight would reach the urn at any time. The symbolism may have shown that it was providing its own light, even on this important day of renewal in the solar calendar.
A photograph taken by Gibson and Sons at the time of the excavation shows a possible blocking stone at the start of the passageway, which would have further limited light down the passage on the solstice. There is no evidence remaining of this stone now, so it is difficult to understand the overall effect this would have had on limiting light at the solstice. It is worth remembering that the final resting place of this urn probably came after a life of servitude. The urn in Kent had traces of animal fats within it and was probably used as a transportation vessel for food before its final role as a funerary urn.
Trevisker style urns are not the only vessels to include crosses on their base. Although in general this cruciform addition to urns is rare and seems to be reserved for the more decorative funerary examples. Other examples of cross based urns have been found in Ireland, Scotland and Yorkshire.
As a final thought, I doubt we shall ever know the full truth behind this oddity in the design, but it is a nice idea to consider that the cross was added by our ancestors to bring light to the darkest of places.

Cahill, M. (2015) Here comes the Sun – Solar symbolism in Early Bronze Age Ireland. Archaeology Ireland 29(1), 26-33,, 2015.

Jones, A and Thomas, C (2010) Bosiliack and a reconsideration of Entrance Graves. Proceedings of the Prehistoric Society. 76, 2010, pp 271-296.

Kavanagh, R (1973) The Encrusted Urn in Ireland, Proceedings of the Royal Irish Academy: Archaeology, Culture, History, Literature, Vol. 73 (1973), pp. 507-617

Wolf Moon – Supermoon over Cornwall

On By cornishstargazerIn Uncategorized2 Comments

 

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Men-an-Tol – Supermoon

 

Yesterday the evening had a break in the clouds from the run of stormy weather we have been having in West Cornwall. This gave me the opportunity to get out and try and image the supermoon over an ancient monument. The intention was to image the supermoon at a stone circle so the picture can be used for my forthcoming book on archaeoastronomy and the stone circles in West Cornwall. I knew that Boskednan would give a great horizon for the supermoon to rise above so that became my destination of choice. I knew the moor would be muddy, so I decided to park closer to Men-an-Tol rather than walk in from Ding Dong mine. Although this was a longer walk it would mean that I could also image Men-an-Tol if needed. Wow, I hadn’t expected the whole Moor to be a quagmire – it was virtually impassable in places and perhaps the wettest I had ever seen it.

 

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Boskednan

 

The picture of Boskednan shows how wet the ground is. The Sun is setting in among the cloud – low in the Southwest. This is near to the position that the sun would set at the winter solstice, over the clearly placed Boswens Menhir.  At Boskednan it was obvious that the cloud to the east of the site was pretty thick but above this bank of cloud, there were clear skies forming. As Men-an-Tol is down the hill from Boskednan I decided that this lower altitude may give the sky clearance from the cloud bank. Setting off back down the hill my walking boots decided to give up with the sole coming away from the boot at the toe -(RIP boots you have served me well – travelling mile upon mile over this landscape!!). So, making a decidedly flapping noise in the wet I gingerly set about getting down the hill to Men-an-Tol. By the time I reached this lower circle the Sun had set and the Moon had begun to rise. The Moon closest to the winter solstice sunset rises and sets in its most northerly position it also rises to its highest altitude. As a supermoon (the Moon is at one of its closest position to Earth) it makes it one of the most impressive celestial sites you can see.  Unfortunately, the cloud didn’t play ball and I only managed to get glimpses of the Moon rising there is a second image below.

 

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Men-an-Tol – Supermoon

 

Local Astronomy History Leaflets

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Bright Stars Dark Skies - Leaflet
Self guided tours for John Couch Adams and The Hurlers in Cornwall

Newly released and in Cornwall you will find two self guided tours. The first looks at local astronomy hero John Couch Adams and takes you on a self guided trip around his home area based in Laneast and Launceston. There is lots of information about the man and his achievements and sites to be seen along the way.

The second leaflet is a tour of the Hurlers. Once again self guided, it takes you around the immediate sites. It looks at the recent archaeoastronomy developments for the sites.

These leaflets have been produced as part of a Heritage Lottery funded project by Bright Stars Dark Skies. Grab one while they last!!

Boskednan circle and Carn Galver

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Boskednan circle is located on a ridge near New Mill north of Penzance. Here is an image looking towards Carn Galver a local easily recognisable outcrop. The summer solstice sunset imaged falls to the south of this outcrop onto an area known as watch croft. But what is interesting is that a Lunar Major Northern setting point would be directly on the Carn itself, as it measures 318 degrees. Could this have been built as a lunar observatory? rather than a solar one?IMG_5733

Other circles in the area have links to the lunar cycle, The Merry Maidens also has a local outcrop in the lunar major setting position and Boscawen-un has lunar links with its quartz stone and positioning of a menhir (standing stone) in the lunar northern rising position. All these discoveries and much more are being compiled and will be released in a book dedicated to wonderful circles found here in West Penwith, within the new year.  I will keep you all posted.

Rare pair of Astronomy themed tokens

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Tokens were issued in England from 1648. They were used to pay for goods and services – a replacement to coin. This was partly due to the country having no monarchy, Charles I having lost his head, leading to a republic headed up by Oliver Cromwell. How could England have coins when there was no monarchy to put on them? It was also due to the lack of coin available for people to use, leading them to make their own. The practice was outlawed in 1772.

A huge range of tokens were made but I know of only two with an astronomy link. One is in the British Museum  Issued in 1666 by Richard Berry it shows 3 men with astronomical instruments. Possibly depicting a pub called The Astronomers from the dockside in London.

http://www.britishmuseum.org/research/collection_online/collection_object_details.aspx?objectId=1242148&partId=1&searchText=Astronomy&page=1

The other was issued in Maidstone Kent by Thomas Swinoke and is in the image below. It shows 3 men one with a globe and 2 with scientific instruments, possibly telescopes. It is possible that it depicts the pub the Worlds End.


More information can be found on 17th-century tokens here http://www.thecoppercorner.com/history/17thC_hist.html

A 6 tailed comet

On By cornishstargazerIn Uncategorized1 Comment

On the 1st March 1744 comet C/1743 X1 reached perihelion.  Although only the 6th brightest recorded comet.  It will be remembered for its striking 6 tails which developed.  It reached a blazing apparent magnitude of -7 and was visible during daylight, after it passed by the sun a relatively close 0.2 AU.  It has been suggested that the multiple tails occurred due the at least 3 active nucleus, maybe as the comet tore itself apart during perihelion.

It was spotted by a young Charles Messier on whom it had a great effect and lead him down the road of becoming an astronomer.

Comets as bright as these are rare events.  A similar but more recent example was comet Mcnaught or the great comet of 2007 as it became known.

DeCheseauxklinkenberg