The National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA) is an Italian Government sponsored research and development agency. In 2017 Sara Bollanti and her team at ENEA in Frascati developed a solar compass that "is 100 times more precise than magnetic compasses..." with applications for surveying, civil engineering, and for us, sundial alignment. The heart of the device is a combination of GPS receiver for determining both time and geographic position and a solar collector consisting of a narrow slit and a CMOS image detector. Essentially this is an electronic solar azimuth compass. A smallArduino computer uses the UTC time plus geographic coordinates to compute the local sun azimuth and then compares it to the position of the sun's projection of a slit on a CMOS detector. According to ENEA, the "...electronic solar compass is compact, completely automatic, cheap, and reaches an accuracy better than 1 arcmin. The latter is one of the best currently available values, comparable to those achievable by means of much more expensive and sophisticated devices, like coupled GPS systems (see for example U.S. patent 5,617,317A, 1997) or gyrocompasses. Furthermore, the ENEA compass provides the orientation in a few seconds, a time extremely shorter than that necessary for gyrocompasses."
By 2018 this was tested in Antarctica and now the mathematics has been reduced to fit into your smart phone. In April 2020 the ENEA team announced the developed the smartphone app i called "SunPass". It is currently in beta testing and will soon be available at the Play Store. In basic form, the app allows you to acquire the sun azimuth by pointing toward the shadow of a vertical object such as a building ("shadow method") or the shadow of a vertical pole ("gnomon method"). A more accurate appraoch is to construct a box with a slit on the front and hole on top such that the smartphone can observe the illuminated sun line on the floor of the box ("Slit method"). For the advanced, one can construct a precision holder from a kit that mounts on a tripod.
ENEA's goal of a low cost, simple method of precision alignment is now accessible to all. This new technology implements the mathematics of determining the sun's azimuth in elegant ways. But of course it only works on sunny days.
|Photo Credit: Andrew Thompson|
Archaeologists have found two miniature stone engravings in a cave on the island of Sulawesi in Indonesia. One plaquette appears to be a sunburst, the other an ibex like animal, the anoa. These pocket-sized carvings dating back between 14,000 and 26,000 years. Elsewhere in Sulawesi the oldest cave art dating to 44,000 years ago was recently discovered, dispelling the Euro-centric notion of Pleistocene art.
Examining the incisions cut into the ancient flowstone, the Sunburst hexegon outline was carved starting in the photo from upper left, with continuing connecting lines done clockwise. Then the 7 rays were added. Small traces of a red mineral (perhaps red ochre pigment) exist in some of the sunburst cuts, possibly indicating that the sun was enhanced in a beautiful red color. Before this discovery the oldest known depiction of the sun was from the Nebra sky disk found in Germany and fabricated of metal only 3,600 years ago, rivaling Pharaoh Akenaten who built a whole city to the glory of the sun (Aten) 2,340 years ago.
The archaeology team was lead by Michelle C. Langley of the Australian Research Centre for Human Evolution, Griffith University, with associates at Arkeologi Nasional (ARKENAS), Jakarta, Balai Arkeologi Sulawesi Selatan and Balai Pelestarian Cagar Budaya in Makassar. They report in Nature Human Behaviour "... the discovery of two small stone ‘plaquettes’ incised with figurative imagery dating to 26–14 ka from Leang Bulu Bettue, Sulawesi. [The pocket-art was discovered in a cave and rockshelter complex of Leang Bulu Bettue (4° 59' 31.18" S, 119° 40' 5.53" E) situated at the foot of a limestone tower in the Maros-Pangkep karst area.] These new findings, together with the recent discovery of rock art dating to at least 40 ka in this same region, overturns the long-held belief that the first H. sapiens of Southeast Asia–Australasia did not create sophisticated art and further cements the importance of this behaviour for our species’ ability to overcome environmental and social challenges."
The artefacts reported here are currently curated at the Australian Research Centre for Human Evolution, Griffith University, Nathan, Australia. They will return to Indonesia at the conclusion of the project where they will be given accession numbers and be curated in Makassar by Balai Arkeologi Sulawesi Selatan.
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Several years ago in 2017 archaeologists found a rare hemicyclium sundial. Now another hemicyclium in excellent condition has been unearthed in Turkey's city of Denizli. Celal Simsek, chief archaeologist at Denizli's Pamukkale University, calls it "unique". A better word is rare. Less than a hundred examples of this type of Hellenistic sundial have survived. It was found in the ancient city of Laodicea about 370 miles south of Istanbul. The sundial seems to have come from the archaeological site of one of the temples. As reported in the Daily Sabah, "Among the rare, largely preserved buildings in the city are the largest ancient stadium in Turkey, a theater and a sacred agora." The hemicyclium of pink marble has an outer edge decorated in foliage while the interior hemisphere has the traditional Greek names of the seasons. Hour lines deliniate the time. Almacantor lines show the solstices and a great circle marks the equinox. In AA Photo of the sundial at right, a needle gnomon has been restored to show how the sundial casts a shadow. Time and season are read at the gnomon shadow's tip.
Here in Great Falls Virginia on the day of the Spring Equinox, March 19th, it's a rainy day. Perhaps that helps us want to stay inside with all of the travel and meetings restrictions imposed because of the Covid-19 virus. However, astronomical events aren't deferred because of human and biological issues. Late today the sun crosses the celestial equator and heralds in Spring. You can observe this event remotely thanks to Lowell Observatory in Arizona. Lowell Observatory will begin Live Streaming the event starting at 9pm EDT. "The spring equinox in 2020 occurs on Thursday, March 19 at 8:49pm MST/PDT (3:49am GMT), when the Earth's axis is exactly perpendicular to an imaginary line drawn between the Earth and Sun. On the equinox, the Sun rises due east, and it sets due west, no matter where you are on the Earth."
|1918 Photo of Camp Brooks Open-Air Hospital Boston - Nat'l Archives|
We feel the menance of the Corona Virus (Covid-19) and the imposed social isolation. Although worse than the typical annual flu, the Corona Virus pales to the worldwide pandemic of the Spanish Flu (isolated as the H1N1 virus). What does this have to do with sunlight? I am indebted to Richard Hobday's well researched article:
Here is his paragraph on "Sunlight and Influenza Infection"
"Putting infected patients out in the sun may have helped because it inactivates the influenza virus. It also kills bacteria that cause lung and other infections in hospitals. During the First World War, military surgeons routinely used sunlight to heal infected wounds. They knew it was a disinfectant. What they didn’t know is that one advantage of placing patients outside in the sun is they can synthesise vitamin D in their skin if sunlight is strong enough. This was not discovered until the 1920s. Low vitamin D levels are now linked to respiratory infections and may increase susceptibility to influenza. Also, our body’s biological rhythms appear to influence how we resist infections. New research suggests they can alter our inflammatory response to the flu virus. As with vitamin D, at the time of the 1918 pandemic, the important part played by sunlight in synchronizing these rhythms was not known."
It's coming - The 26th Annual North American Sundial Conference. This year from Thursday Aug 6 unti9l Sunday Aug 9th we'll be in Philadelphia within walking distance of Indepencence Hall, The Liberty Bell, The Benjamin Franklin Museum and much more. Make your reservation at the Hilton Garden Inn, Philadelphia Center, 1100 Arch St. Details are in the attached flier.
Each year North American dialists gather to share presentations and displays of sundial projects. Why come? What people have said: "First, and foremost, I have fun! To talk about and cover my ideas on this strange area of imagination with like-minded folks is very rewarding and what a congress of interesting and kind minds! Second, there are real dials to see, admire, and analyze [during our Friday field trip] - all incised in a convenient and comparable way. And these are not the sites usually touted by the locals as meaningful. Finally, there is a local stamp of author on things that are not totally abstract. Where else can one see mathematical ideas?"
Combine your interest in sundials with an immersion in American history and join us to meet old friends, make new acquaintences, and gain gnomonic insights. Another attendee said "The presentations are a chance to brush up on my fading math abilities, inspire the possibilities of new dial creations, and learn odd quirks of history. I always leave the conference eager to start my next dialing project. The bus tour of local dials provides both beautiful dials, many in garden settings, and discusses the foibles of implementing a dial design to remain an accurate timekeeper."
Until May 1st the registration fee for full participation is 325 USD. After May 1st it will cost 350 USD. Sign up now.
We've reported on ancient mosaics from Turkey showing sundials (Antioch Mosaic Sundial - 2016). Now from the Ministry of Sciences and Higher Education in Poland ( Archaeology News - Ancient Sundial and Science in Poland ) another ancient mosaic sundial has been discovered:
Sundial in the Madaba Map, a great mosaic located in Jordan. The sundial is located next to the gate on the left. Credit Wikipedia/public domain.
Professor Marek T. Olszewski from the University of Warsaw was re-examining a number of mosaics dating back to the 2nd century AD when he made his startling discovery.
One of the mosaics from the 6th century AD which was discovered by the Gate of Damascus in Jerusalem, Olszewski noticed that between a richly dressed women, a mysterious object is visible, which scientists at the beginning of the 20th century described as an oil lamp or column.
Olszewski said: ”After careful analysis and comparison with a sundial discovered during excavations, I came to the conclusion that this mosaic and other ones similar to it depict sundials....
Another sundial "tracked" by the Polish researcher is located in a wall mosaic in Santa Cecilia in Trastevere church in Rome. This mosaic was created during the time of Pope Paschal I (817-824).
Prof. Olszewski also noticed a previously unknown sundial in the Madaba Map - a huge floor mosaic, which is currently stored in the church of St. George in Madaba, Jordan. It shows a map of the Middle East from the Byzantine period. This is the oldest cartographic depiction of the Holy Land, including Jerusalem and dates back to the 6th century AD.
Yet another depiction of a sundial comes from Tarsus (Mersin) in Turkey, where a figural mosaic (ca. 2nd-3rd century AD) shows a sundial on a column and a crow sitting on it. A man tries to scare off the bird by throwing a pouch at it (crow was a symbol of a bad omen).
Professor Olszewski has now discovered eight previously unknown sundials in the designs, taking the total number known to 15.
From the Harvard Gazette - Dec 9, 2019 : "Since 1672 Harvard University has been acquiring scientific instruments for teaching and research. In 1948 the Collection of Historical Scientific Instruments was established...[and has] grown to more than 20,000 objects making it one of the three largest university collections of its kind in the world"
As an illustration of the collection is a photograph of ivory pocket sundials shown here, made in Nuremberg, Germany between 1575 and 1645. These elegant diptych sundials represented the 16th and 17th century equivalent of pocket watches, especially for wealthy traveling merchants to keep track of time. "Harvard has the largest collection of sundials in North America, a gift of David P. Wheatland, Class of 1922."
As described by Dr. Sara Schechner in Time of Our Lives - Sundials of the Adler Planetarium who is the David P. Wheatland Curator of Historical Instruments at Harvard describes the diptych as "fashioned from ivory, gilt brass, carved wood, and wood covered by printed paper. The materials offer hints on the social status of their owners. So too do common and novel accessories found on the instruments. A directory of cities and their latitudes suggests an owner who traveled... The association is stronger when the diptych combines a gazetteer with particular sundials that found the time according to the sundry conventions of England, France, Germany, and Italy. A merchant crossing a border would have needed to know how to set up an appointment with his clients. How many hours would there be to transact business or to journey along the road? Calendrical devices on the diptych showed him the length of the day and night throughout the year...[and] the diptych's lunar volvelle gave ...the moon's phase. It also assisted the owner in finding the time by moonlight...[And] a diptych with a magnetic compass [allowed proper and immediate orienting the sundial]."