Bringing Astronomy to Cornwall


 Located at Court Farm Holiday Camp Site, St Stephen, Mid Cornwall PL26 7LE.

Last updated;- 18th April To contact the Observatory Office (01726) 813602 or the Observatory Site  07804 036959. 

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SS Computer Services when you simply need the best - just telephone 01726 68684.





Radio St Austell Bay; listen on 105.6 FM and on line for all the local news and events. Including a monthly contribution

from Roseland Observatory.

Visit the Observatory;-  We have been on the radar for the organisers of youth and adult groups for a while now.

    £6.00 per adult, £4.00 for U 16's and U 8 foc, phone or email for more information.  

For Group bookings for schools, Scout & Guide Association members go to the

News Tab on the top of the page. Please ring (01726) 813602 to book your place. 


The Lyrids ;-  22nd/23rd April. This is good news as we have had a long time to wait since the last shower.  The radiant of this shower is a shade SW of Vega which rises about 9.00pm in the NE. Vega is one of the brightest stars in the sky  and is pretty visible.  As usual the best time to watch is after midnight.  As with all showers there is a parent comet, in this case it is Comet Thatcher,  discovered by Galle in 1861 and the shower  has been recorded since 687 BC.  These days we can expect only a few per hour but some can be pretty bright and leave behind a smoky trail. Lets hope for clear skies. The bright star is Lyra, the meteors appear to come from an area close to it. Image credit Start looking out NOW!















Mars;- Is at Opposition at this time its disk is pretty big in a telescope don't miss the chance to see it at its near best.

BBC Sky at Night;-  May's programme focuses on Mars and the 10 years of Mars Rovers. It is now available on iplayer, don't miss it.

The velocity of Light - National Astronomy Week 2014.

The Background.

It was Ole Romer, the Danish astronomer, who made a set of observations between 1671 & 1677 and based on best estimates of distance at the time to calculate a reasonable figure for the speed of light. The technique he used was based on eclipses of the satellites of Jupiter. Romer like scientists before and after him “stood on the shoulders of giants” to advance his work.



Ole Romer

It was Copernicus in 1543 who suggested that the Earth and all the planets orbited the Sun.


Kepler in 1609 and 10 wrote his 3 laws the last of which stated that T 2 = R 3 this is easy to interpret if T is in years and R in astronomical units. This allowed astronomers to define the distances in terms of the AU for all the planets of the Solar System. Galileo saw the moons of Jupiter in 1610.


In 1678 Newton unravelled gravity G to give a quantitative interpretation of Kepler’s Laws. GCSE Book

Naturally enough Jupiter was studied in detail and the time it took Jupiter’s satellites, Io in particular, to go behind Jupiter in eclipse was measured accurately by Romer.

The image which follows shows Io transiting the planet and also includes the Great RedSpot.


Image Credit Paul Clarke



“The satellites move from east to west across the face of the planet, and from west to east behind it. After conjunction with the Sun and before opposition, the shadow of Jupiter falls to the west, eclipse precedes occultation, and shadow-transit precedes transit. After opposition, the order of the phenomena is reversed, occultation preceding eclipse and transit preceding shadow-transit.” BAA Handbook 2014. Due to fact that Jupiter was past opposition during National Astronomy Week it will only be possible to use the time of emergence of Io the innermost of the moons of Jupiter.An analysis of the times that Io remains eclipsed showed a steady increase from the beginning of January,  when Jupiter was in opposition , until early June when it is in conjunction with the Sun. National Astronomy Week website.  the actual Society running this event for NAW is Orwell AS

To keep an eye on Jupiter the planetarium programme  “Stellarium” not only tells the observer which moon is Io but also the distance of Jupiter from Earth. Over a period of time as the distance increases so does the length of time in eclipse, when two or more results have been obtained the speed of light can be calculated. Clearly the more results obtained the closer we get to a true figure of the speed of light. The plan is to submit timings to Orwell and they will do the calculation!  NB Stellarium can be downloaded from it is free and works on most Computer Platforms.

There was one problem faced by the early astronomers – they were able to obtain comparative figures of distance from the Sun but an absolute distance eluded them. However the transits of Venus 1761 and 1769 allowed rough figures to be obtained. Better figures were obtained in 1874 and 1882 and they were analysed afterwards by Encke. See The Midnight Sky p191 see also Jeremiah Horrocks by Paul Marston. Clearly these events had not yet taken place in the 17th cent so an alternative must have been used.

David Gill. It is well known that Gill in 1877 measured the parallax of Mars on Ascension Island. Dic. Scien Bio.p417. Perhaps this too built on earlier work?

Jean Cassini, although he rejected the idea that light had a finite velocity nevertheless was the first to arrive at a figure for the distance of Mars in 1672. He took advantage of a good (early September) opposition by sending Jean Richer to Cayenne, on the north east coast of South America. Cassini stayed in Paris at the Paris Observatory. This gave a baseline of nearly 10,000 km for a triangulation of Mars. The results derived for the AU were 138 million km about 11.6 million km less than the value accepted today. Dic Scien Bio p221





Illustration of the method

 Ole Romer used Cassini’s results to measure the speed of light. He was aware that the length of time between eclipses of Io was not constant. He calculated the time in 1675 (early June) when Jupiter would be closest to Earth i.e at opposition and observed that at that time the interval between eclipses was also smallest. He continued for a number of years taking measurements. In Sept 1679 he announced that on the 9th November the eclipse would actually take place some 10 minutes later than other astronomers had predicted. He was of course correct and stated that the cause was the extra distance the light had to travel as the distance between the two planets was now larger than before. He calculated the speed at 225,000 km/sec pretty close to today’s figure of rather less than 300,000 km/sec.

 Further reading;- The story of the heavens by Robert Ball pub1890 on P222

Outlines of astronomy by John Herschel pub 1869 on P364.

Astronomy by Flammarion published in French 1880 translated from the French edition 1955-60 translated, revised and updated 1964 P303 et seq.

Current  Courses;- 

                                     Tuesdays Life and death of stars - with Clint.

                                         Tuesdays  Astronomy for Interest - with Brian

                                                           Wednesdays GCSE Astronomy - with Brian                          


Astronomy for interest is our basic entry level course for new comers to the sport. Life and death of stars is a little lower than A Level

All courses start;- at 7.00pm and finish at 9.00pm and are £5.00 per night. Courses are 10 weeks long except the GCSE which runs until May.  "Astronomy for interest" and "Life and death of stars" on Tuesday   GCSE Astronomy Wednesday.  Contact Brian Sheen (01726) 813602.  email

Work experience for years 10 & up;- Interested students should contact their school coordinator as soon as possible. See also the News Page. All letters and correspondence must go to the Par Office, 92 Par Green, PL24 2AG. and not the Observatory site.  We are  recruiting for 2014 now!

UK's very own Space Weather forecast;- From the Met Office Exeter will come the UK first Spaceweather forecasts, they will start in May 2014 i.e in a matter of days.

Naturally RAL Space the source of many of the instruments on the various Solar Observatories is heavily involved.  However we will have to wait before Solar Orbiter launches in January 2017 to get our closest views of our Star.


Prominences and active areas on the surface of the Sun.

An archive image taken through our H Alpha scope.

Mike in the Shetlands; - my main man up there has got his new website  running well - check it out it even links back to this one! He has just added Curiosity to his range of card models you can down load for free. Please note this one is 101 MB - just like the Dalmations.

For the work we did together at Stargazing LIVE 2013 Mike made a model rover as a prize that was won by Thomas. Saw the lad again last week and he has the Rover proudly displayed in his room!


 Mike's model of Curiosity - this one is in Shetland not Mars.

Bodiggy School paid us a visit a few days ago here is some of the evidence







April Night Sky

Don’t miss it;- Mars is the "star" of the month – the original "wandering star" no less. It is at its closest to us for the next two years, given clear skies it will be possible to see the Polar Caps and some of the dark patches on its surface. The Observatory will have some of its scopes focused on the Red Planet most clear nights, just check before turning up.

Constellations;- This month sees a welcome return of Deneb and Vega two stars of the "Summer Triangle" a sure sign that Spring is here. Take the opportunity to look for M13 in the keystone of Hercules the giant globular cluster can be seen with a binocular or small telescope. April is one of the better months for being out of doors. It is not so cold and yet is gets dark at a reasonable hour.

The Moon;-, New Moon 30th (March) , First Quarter 7th, Full Moon 15th., Last Quarter 22th, New Moon 29th. Total eclipse of the Moon on the 15th - visible over most of the world except the UK.

The Sun;- An Annular eclipse of the Sun on the 29th - visible as a partial in Australia.

Note the linkage between the Lunar and Solar eclipses it is not a coincidence!

The Planets;-

Mars;- At its best for two years - close to the bright star Spica in Virgo. Really good for most of the month, it will be good to catch a glimpse of its distinctive features in a telescope.

Jupiter;- rises in the East and is up most of the night– check out its four moons and watch them dance around the planet night by night. It is now past its best but always a great object in a telescope.

Saturn;- Is in Libra and therefore close to the horizon when seen from the UK, never the less its rings are always good to see.

Meteor Shower;- The first meteor shower for a while, the Lyrids peak on the 22nd but can be picked up a few days either side of this date.

International Space Station; As usual check exact times from

Astronautics Badge;- The UK Space Agency have sponsored a new Scout Badge. We are investigating the best way of delivering this to Cornish Scouts.

The Hurlers;- A combined project with the county archaeologists culminated in a nine day "Summer School" on the Hurlers. Called "Mapping the Sun" Involved survey work and mapping the Sun rise and set positions. We have created a Bronze Age Landscape map - working with a range of specialist kit new and old to achieve this. New Discoveries were made and new Legends were born. The archaeologists uncovered, examined, photographed and recorded a quartz pavement that last saw the light of day in 1938 and using modern techniques will learn so much more. Some of our research work can be found on this page see below;-

Orion's Belt on Bodmin Moor.

The image was taken, with great expertise, by Tony Piper located on  Caradon Hill. Single torches were placed in each of the circles. The result shows how closely the torches resemble the stars in Orion's Belt.


This lovely sunset picture showing two of the Hurlers lit torches was taken by Paul Hughes of the Observatory team

Stop Press - Equinox problem solved.  The Sun did not rise and set as expected this problem has now been addressed with a little help from my friends.

NB The first rough draft has been prepared, images have now been inserted and then GPS and other data. It will then be released on macastro. Watch this space!



Martin, a German visitor to Cornwall filming the Hurlers from his Quadrocopter.

His You Tube videos can be found on Thesnaptin

 Image Credit Robin Paris

On this web site;- Much further down this page you will find an account of some the research that has gone before. 

Good News;- The Par Community Association has been supported by a grant of £660.00 towards installing the Sphere. Cornwall Council is working out the best way to get the Sphere sited to great advantage. Now getting down to a Business Plan! Now have quotes in and a number of options so things are on the move.

Part of the Paralympics is in Cornwall - it is an Armillary Sphere

Image credit Sonia Clyne.


Joe Warrener who spent a few nights at Court Farm took this excellent view across the site.




The Pelican Nebula an emission nebula in Cygnus.


Image Credit Paul Hughes


To see all of Paul's images at full resolution go to  a lot of detail has been lost on the web page. His favourites file can be run as a slide show covering a range of deep sky objects.  





If you go down to the woods tonight .....! Image credit Anne-Marie


Shetland Astronomical  Society;   I was in Shetland in the summer 2011 working with the SAS.  Check out   To see Mike's - austroastro's video made from Chris Brown's images of the Northern Lights click on the link. For other U tube videos by austroastro do a Google search.


Science Technology Engineering Maths Ambassador;-  or STEM for short. Mainly for those wishing to get involved teaching with the Observatory. This is a National approval scheme that allows us to teach/demonstrate in schools and youth groups. Any one can apply (including those outside our team) is is good for those asked to go into schools to represent the companies they work for, Includes a DBS.  To learn more contact us via any of the Observatory links.

A great link from an American fan;-  Matthew H. found A kids Space Centre - Fun with Model Rockets - ( while working with his local library.


Mike working on the magnetometer

 An image credit Rob Stidston

Have your telescope in two places at once? Well with Slooh you can.

A good way to be able to image almost anywhere any time with your "own" Robotic Telescope. The Observatory has a "Commander" Membership.   


 The ISS;-  

The Space Station  is visible in our  skies  from time to time. See for exact times for you.   There are chances to see it in the daytime and towards dusk when it is getting dimsy.  

It Is so bright that it will flare as the Sun strikes one or two of the large solar arrays.     H-A are now giving suitable times for daylight passes. 

   Regular Opportunities for schools

 For more information about the courses see the "NEWS" page and then contact the Observatory.   

Work Experience years 10 & 12;- Our very successful WE programme enables students to take a genuine part in the work of the observatory as trainee astronomers. Apply now for 2014 to the Par Green address and not the Observatory site.

  Key Stage One, Two and Three Astronomy. Opportunities throughout the Year  just phone and book, more  under News page on this site.

 Earth & Beyond; Doing Space this term then school teachers should see our News section. 

Gifted & Talented sessions for years 10 & 12 at the Observatory.

GCSE Astronomy Practical Project work. Having successfully guided many students through the GCSE Course work we  offer opportunities on a regular basis. Opportunities throughout the year  just phone and book. Only £5.00 per session. In each case email or phone (01726) 813602 to learn more.  

 Extended project A Level std. Global Dimming. This experiment was extended this year into the IR as it  produced a clearly measurable change in light levels through the previous Christmas period.

 For Scouts, Guides and other youth groups see the separate News Page.




 The Neptune Saga;- Continues with a new book about Le Verrier which fills a black hole in our knowledge of 19th cent. French Astronomy.  Written  a review for publication in a number of journals. Also the long awaited paper on the subject has now been published see below in the main Neptune section. Anyone wishing to read it please request a PDF copy.

 Our Neptune research has reached the august pages of the Antiquarian Astronomer issue 7 March 2013.  it covers some 11 pages and is described as "incisive".



 Taken during the Society for the History of Astronomy autumn conference 2011.

Neptune's special year;- The year 2010 opened in January with a special presentation in Seattle, USA. NB The Blue Planet is close to opposition at the moment so a good time to observe given clear skies.

Image credit "a friend" 

Note the Cornish Flag!





Neptune from Voyager  2                         Credit;- Jocelyn Murgatroyd and Cornish Cross Laneast












Images by John Chiswell from two cameo reliefs. The lady is Eliza Adams nee Bruce  - It is believed to be the only likeness in existence. The sculpture was by Albert Bruce-Joy a relative and well known artist.



This image is of the memorial in Westminster Abbey and is also by Bruce Joy. Image Credit Westminster Abbey.


 Bill Sheehan's Neptune  with 10" RC.


Neptune discovery story. For a short film of the Neptune story visit Maarten Roos website. 

Have continued my researches by contacting the Chinese University in Hong Kong (been there got the T.Shirt). Some 10 years ago they did some excellent work on Neptune's orbit which I now have permission to use in my talks.

For Canoe Africa see below.

The Hurlers;- 

World Heritage Site;- We are currently working with Caradon Archaeology on The Hurlers.  (Minions is the  nearest village) This work is centred on how to best interpret these ancient sites to an interested general public. At the moment we are helping with an APP to interpret the area in a modern way. Thanks to Cornwall Council and Cornwall Heritage Trust for their support. The App is now on a an APP store but in a Beta Version to be tested by those involved.

The  background;-  The Hurlers can be found on Google Earth 500 30' 58.67"N   40 27' 29.69" W, the aerial view is  supplemented by a number of photographs and some text. Until recently people studying the various monuments around the country would look closely at one aspect or site and not regard those near by. The Hurlers are the focus of a much larger complex of ancient structures.

Back to the Hurlers. Lead by Gary and supported by Amanda we measured the elevation of Rillaton Barrow above the horizon step by step using a professional level.  We had good results although more work needs to be done. We have proved which star it celebrates and when it was built. We seem to have identified the Processional Way referred to by John Barnatt in "Prehistoric Cornwall".

The Calendar Stone is to be found in the Centre Circle and to the south of centre. For all time people  have noted that shadows cast by trees or stones change their length and direction during the day and throughout the year. The length marked at midday once a month requires only 7 marks to define the solar year. A more complete explanation of this system is available.

Archaeologists are often rightly sceptical of two point alignments and require either a Back Sight or Fore Sight to support the evidence. Extend the Hurlers SW - NE line northwards about a kilometre to arrive at Tumuli. Due north is Stowe Hill due  south is Minions Mound with more Tumuli. (Tumuli are Bronze Age burial sites.) Due East is Kit Hill due west is a large barrow. If you turn your back on Kit Hill and look towards the Pipers you will find they lie one behind the other i.e. due west. Stand between the Pipers and look towards Stowe Hill and you look North. Are the Pipers contemporary with the Hurlers - the evidence points in a positive direction. 

The N - S line can be extended on to Long Tom,  Menhirs or Long Stones predate Stone Circles and this one has had a Cross carved on it at a later date. Although not exactly due south of the Hurlers it is south of Stowe Hill which is a long ridge of high ground.

Vernal Equinox;- To celebrate this we  visited the Hurlers  on the Sunday 25th March 2012    Sunday AM was good in that it was clear and we saw the Sunrise, close to Kit Hill although Kit Hill itself was not visible to the naked eye due to general murk. Sunday PM saw the Sun setting due west close to a couple of burial mounds as predicted. 

Summer Solstice;- It so happens that the midsummer Sun rises above Stowe's Hill and sets over Brown Willy. Summer Solstice 21st June and we were at Craddock Moor Circle for the event.  A first for us was an observation of a special Standing Stone on Stowe Hill It seemed to mark the actual position of sunrise. (June 2010)

From Craddock Circle the Sun rose behind the Cheesewring on Stowe Hill as predicted, what was new to me was to see the Sun hitting Tregarrick Tor before it rose for us, this confirms that Tregarrick marks the winter solstice sun set. (June 20th 2012)



                                      The Sun rising over Stowe Hill    (2012)                                       

Image by Amanda King of the Roseland Team.


Summer Solstice 2013;- The group ambled out Craddock Circle. It is a circle of fallen stones close to gorse bush atop a featureless hillock. The Sun had shown signs of remaining visible until sunset but it was not to be. However it appears to set just west of Brown Willy. Images had been taken a couple of days before and will be examined in the Observatory.








7th June                                                                                                             19th June

Many thanks indeed for the images from Robin Paris of Darite - excellent and revealing sunsets. A CD has just arrived with more images all adding to our overall knowledge of the Bronze Age calendar.

Autumnal Equinox;- The Sun rose and set as per the Vernal Equinox, although on the date we were there (21st Sept. 2011) the fog was so thick it was impossible to see across the Circles!

This time using a solar filter in conjunction with a small telescope it was possible to determine that the Sun rose just a bit to the right of Kit Hill stack. The sunset was impossible due to thick cloud. 22nd Sept 2012. Same situation Sept 2013.

Winter Solstice;- The three stone circles known as the Hurlers near Minions, Bodmin Moor. Appear to mirror the well known asterism of Orion’s Belt in the centre of the Orion constellation.

21st Dec Mid Winter Solstice 2013;-  Usual pea souper of course up on the Hurlers - Bodmin Moor, so we were unable to do much until after breakfast. The modified compass worked well to gave us a real baseline for the first time. Checked out Kit Hill again as due East and established the position of the "4th circle". We were unable to do the Sun rise from Craddock Circle. Just too foggy at sunrise.

In the 21st cent. this constellation, including Orion’s Belt, is due south of the Hurlers on the  winter solstice (Dec 21st) at midnight. In the Bronze Age circa 2000 BC this transit occurred earlier in the evening due to precession.  Remember the actual day of the winter solstice was marked from Craddock Circle. Due north was marked by Stowe's Pound and the “ever present” pole star, in those days Thuban in Draco and later Kocab in Ursa Minor. Directly north of the Hurlers is Stowe Hill with its Neolithic enclosure and Rillaton Barrow, the Bronze Age users of the Hurlers would have recognized that the stars directly above the Hill did not move and were therefore special. Today the star that occupies that place is called the Pole Star, North Star or Polaris.

 There is no doubt that the view of the Hurlers would have been very special before the Quarry removed much of the viewing area. However even today the torch lit Circles look impressive indeed.


             Paul Hughes of the Observatory Imaging Team

The Three Circles lit by torches, giving a very atmospheric effect.  It seems that at this time the winter solstice was celebrated all over Europe by the lighting of bonfires. It consists of four individual images merged into one.  It was normal for special events to be marked by lighting fires. We carry this practice forward today with our Torch Light Processions and lights on Christmas Trees and in public places.

The role of Craddock Stone Circle;- One question often asked is, how did the people of 2000BC know which was the shortest day of the year? It just happens that one of very few winter solstice alignments on the Moor is between the nearby Craddock Stone Circle (1 kilometre distant) and Tregarrick Tor.  There is even a raised embankment avenue joining the Stone Circle to the Hurlers complex - problem solved.

Clearly the Hurlers were very important in the Bronze Age and this should be more widely recognized and appreciated.

 Update;- A summary of work carried out in the county appears in "The Hurlers an Archaeological Assessment" published by the Historic Environment Dept of Cornwall Council.


 The  papers on precession and the second on astronomy on Bodmin Moor down the ages are on hold at the moment.

Canoe Africa;-  To find out more about my attempt to spread the astronomy word  click on my link Canoe Africa   and visit our special Canoe Africa page. See also check out the reports filed under IYA 2009. The dates are Sept 9th 2008 and Feb 12th 2009 - Thanks to Tammy Plotner.  




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