www.standingstones.org

www.standingstones.org is a resource site for people who want to study Archaeoastronomy for Stone Circles, Standing Stones, Stone Rows and Henges.

The Viewer

Maps of European Standing Stones

Country Areas/Counties/Regions Other areas and comments
Map of UK and Northern Ireland sites
Counties
Wales
England
Scotland
Northern Ireland
Map of Isle of Man
Map of Guernsey
Map of Jersey
Map of Ireland
Counties
Map of France
Departments
Map of Spain
Regions
Map of Belgium
Regions
Map of Czech Republic
Regions
Map of Poland
Regions
Map of Germany
Regions
Map of Greece
Regions
Map of Portugal
Regions
Map of Norway
Regions
Data NOT available for locations above 60 degrees latitude
Map of Sweden
Regions
Map of Switzerland
Regions
Map of Malta
Regions
Map of Italy
Regions
Map of Denmark
Regions
Map of Netherlands
Regions
Map of Specials (UK)

Archaeoastronomy (also spelled archeoastronomy) is the study of how people in the past have understood the phenomena in the sky, how they used these phenomena and what role the sky played in their cultures.

www.StandingStones.Org providers a viewer to display the historic rising and setting points of the Sun and Moon - Viewer

Most of the source data for the site is sourced from the Megalithic Portal and would like to thank the Megalithic Portal for use of this data.

The viewer has data accumulated from around 4000 sites across the UK and Ireland and many others from the rest of Europe including many Stone Circles, Standing Stones, Stone Rows and Henges.
The viewer uses uses the SRTM (Shuttle Radar Topography Mission) based data. Within the UK, the SRTM data is augmented with the Ordinace Survey (OS) based 50m map data. For Latitudes above 60 degrees (Shetland is mainly north of this) then OS data only is used.
The SRTM data is easier to process and generally produces cleaner results than the OS data although the SRTM data sometimes can vary from actual maximum heights by around 20m due to an average being taken across a tile (For instance, the SRTM tile for the summit of Snowdon is 20m below the top). The OS data is composed of 10M contour lines so provides better accuracy on steep slopes while the SRTM data is probably more useful on less steep terrain and hence both are used in conjunction. Spot heights where shown are from the OS data.

More details on most of the sites can be found at The Megalithic Portal.
Another useful reference site for many sites is The Modern Antiquarian.
Studies of the Stones Rows of Britain The Stones Rows of Great Britain.
Megalithomania.com includes all sorts of historic and prehistoric sites across Ireland, including Neolithic, Bronze Age, Early Christian and Medieval monuments. Megalithomania.com.

Sample Images - Syre A - Grid Ref NC680430

The following are example images taken from a Circle in Scotland (Syre) and show how the location could have been used to observe the sun and moon at different positions.
The Winter Solstice setting of the sun
Syre A_4000_NC680430_WinterSolstice.jpg
Major Lunar Standstill (-E-I) rising and setting
Syre A_4000_NC680430_Moon-E-I.jpg

Goals

The goal of the viewer is to show the view from a monument and overlay the rising and setting positions of the Sun and Moon.
The site attempts to make study of these sites easier and provides a generally accurate representation of what could be observed historically from a site.
For the Sun, the Winter and Summer Solstices and Equinox positions are shown
For the Moon the Major and Minor Lunar Standstill are shown (+E+I, +E-I, -E+I and -E-I)

Solstice and Equinox Positions

A solstice is an event occurring when the Sun appears to reach its most northerly or southerly position. The Solstices take place in Winter (about December 21) and Summer (about June 21)
An equinox is the moment at which the center of the visible Sun is directly above the Equator. The equinoxes take place in Spring (around 20 March) and Autumn (about 23 September)

Lunar Standstills and Eclipses

A major Lunar Standstill occurs when the moon stops on a declination of approximately 28.725° north/south.
There is an eclipse season near the March equinox with solar and lunar eclipses at an odd numbered saros.
There is an eclipse season near the September equinox with solar and lunar eclipses at an even numbered saros.
A minor Lunar Standstill occurs when the moon stops on a declination of approximately 18.134° north/south.
There is an eclipse season near the March equinox with solar and lunar eclipses at an even numbered saros.
There is an eclipse season near the September equinox with solar and lunar eclipses at an odd numbered saros.

SRTM and OS OpenData

The Viewer uses SRTM (Shuttle Radar Topography Mission) data published by NASA together with OpenData vector data published by the OS - "Contains OS data © Crown copyright and database right (2019)". For more informtion see OS OpenData acknowledgements

GPX Data

The Viewer also contains links to GPX files for each location. These files allow you to see where on a map the various rising and setting points of the Sun and Moon are. This allows you to pinpoint a foresight such as mountain or hill where the event occurred.
On Windows 10, you can install a GPX viewer with the following link. Other web based viewers are available such as Ride With GPS.

Using the Viewer

The viewer can take several parameters including the following:
name=string - this is a case insenstive search string.
country=Country Code (IM,GG,JE,IE,FR,BE,CZ,PL,DE,GR,PT,NO,SE,CH,ES,MT,IT,DK,NL,UK,XX).
area=County - the area of the country
type=All|Stone Circle|Standing Stones|Standing Stone (Menhir)|Stone Row - Alignment|Henge
grid=None|grid|fgrid - Specify whether to include a grid (1 degree intervals) or a fine grid (10 minute intervals).
res=High|Med|Low - Specify the image resolution (120, 60 or 30 pixels per degree).
label=None|labels - Display spot heights from OS Maps if available.
year=3700|4000|4500|5000 - Select the year - either 1750BC (3750), 2000BC (4000), 2500BC, (4500) or 3000BC (5000).

A type URL would be something like the following
http://www.standingstones.org/viewer.html?grid=grid&res=High&label=labels&year=5000&area=Gwynedd

The mathematics behind the Viewer

Elevation and Azimuth of the Sun/Moon

Formula for the calculating the Elevation and Azimuth of the Sun/Moon
https://astronomy.stackexchange.com/questions/1855/how-to-get-the-longitude-latitude-from-solar-zenith-azimuth
I assume that the earth has a circular orbit when calculating the size of the sun to draw and similarly the moon.

Adjusting for Parallelax

Parallelax for both the sun and moon is calculated although only the values for the moon are significant. Only the mean parallex of the moon is used which at the horizon is about 57′. The Parallelax variation due to the moon's eliptical orbit can vary by around +-3′ but this is not currently displayed
https://en.wikipedia.org/wiki/Orbit_of_the_Moon

Adjusting for Refraction

The formula for Refraction is the following Sæmundsson equation, taken from the wikipedia page which is accurate to around 0.1′ at 10 °C https://en.wikipedia.org/wiki/Atmospheric_refraction
refraction.jpg

Adjusting for Moon "Wobble"

The moon has an additional wobble with a 173.3 day period of approximately +-9′ - this is displayed on either side of the moon as a series of dots.

Drawing the Landscape

The main formulas used when calculating what to draw is the Aviation Formulary and Haversine formulas
from: Ed Williams' Aviation Formulary
https://edwilliams.org/avform.htm
Haversine formula is used to Calculate distance (in m) between two points specified by latitude/longitude (in numeric degrees).
https://en.wikipedia.org/wiki/Haversine_formula

Copyright

Copyright David Hoyle 2019