What's New Under The Sun
Prosciutto di Portici Sundial's Owner
Tuesday, 10 June 2025 18:51
Prosciutto di Portici (Ham) Sundial
Photo: Getty Images
The Prosciutto di Portici Sundial, more often called the Portici Ham Sundial, dates from the first century somewhere between 8 BCE to 79 CE. This small silvered bronze dial was uncovered on 11 June, 1755 in the ruins of Herculaneum (current day Portici) in the "Villa of the Papyri", buried in...
Hamilton Dial Dedicated
Friday, 06 June 2025 21:01
Sundial dedication May 31, 2025. At left is Kathleen Stuckey Fox, with the City Proclamation presented by Mayor Pat Moeller and City Council on-lookers Carla Fiehrer and Susan Vaughn offering congratulations.
On May 31, 2025 at 1pm, the Hamilton, Ohio, sundial (NASS Sundial Registry #1109) was re-dedicated in Monument Park. Originally dedicated in 1941 to the...
Frans Maes Received a Royal Decoration
Monday, 24 March 2025 21:33
Several years ago Frans decided to write the course on sundials that included self assessment questions to force students not only to read the text, but to internalize the concepts. And a final submittal question "not necessarily a difficult question, but: no answer, no new lesson." Thus Frans Maes began writing lessons and sending them out to students.
NASS has now used his material to create...
Pros and Cons of Daylight Savings Time
Monday, 24 March 2025 15:37
In a 24 March 2025 article from the on-line Science Advisor (American Association for the Advancement of Science) Phie Jacobs summarizes the "great debate" of the yearly shift from standard time to daylight savings time. In January 2025 the US Senate introduced the Sunshine Protection Act to permanently have daylight savings time year round. Certainly 54% of Americans do not like the...
Native American Moon Alignment Ring
Friday, 21 March 2025 19:26
Perhaps the most famous alignment circle in the United States is the Cahokia Woodhenge near St. Louis constructed between 700-1400 CE by Cahokia Indigenous native Americans. But there were an estimated 10,000 other earthen mounds that once were scatter across the mid-west..
In an article from Atlas Obscura (https://www.atlasobscura.com/articles/octagon-earthworks-ohio) by Olivia Young on March...
Hamilton Dial under Restoration
Friday, 21 March 2025 18:37
The Hamilton dial is in the restorative care of Jarrett and Celene Hawkins (Hawkins & Hawkins Custom, LLC in Cincinnati Ohio https://www.studio-hawkins.com/) in preparation for the dial's dedication on Saturday, May 31, 2025.
The face of the Hamilton Grand Army of the Republic (GAR) sundial has been cleaned and bead-blasted showing the dial as it was cast 84 years ago. In the process,...
Register for the 2025 NASS Conference
Tuesday, 11 February 2025 00:27
We will celebrate our 30th annual NASS Sundial Conference in Ottawa, Ontario 7-10 August 2025. But you need to register by April 15th to get theFull and Partial attendee rates at a discount. We will be staying at Le Germain Hotel Ottawa, 30 Daly Avenue, Ottawa ON Canada. We have a block of rooms at a discount daily room rate of 284 CAD (approx. 216 USD) plus HST and MAT taxes. ...
VSSC Space Museum gets Polar Sundial
Tuesday, 17 December 2024 23:47
In November 2024, a team consisting of members from SPL, TTDG and CMD of VSSC successfully designed and installed an accurate and fully functional sundial at the Rocket Garden of VSSC Space Museum, Thumba (8.53°N, 76.86°E). Following a space theme, the vertical gnomon is a 3-stage rocket that casts its daily and seasonal shadow on a dial face 1 1/2 meters by 1 meter. The the sundial face...
Historic Sundials of Andalusia
Saturday, 16 November 2024 00:07
Esteban Martínez Almirón has published a new book Historical Sundials: Forgotten Andalusian Treasures (Relojes de Sol Históricos Tesoros Andaluces Olvidados) In it he reviews over 400 sundials from the Andalucian region of southern Spain Originally to celebrate the 25th year of the website https://relojandalusi.org/
Esteban Martínez Almirón began showing his sundial drawings on the site....
Shelbyville Sundial
Wednesday, 13 November 2024 19:36
It isn't often that a sundial face is created before the gnomon is attached. In Shelbyville IN a large, circular art piece in the form of a sundial, was created at the Blue River Trailhead early in 2024. If they had chosen an analemmatic sundial, a walker of the trail could have simply stood on the appropriate date and used his or her own shadow to tell the local solar time. ...
Sun Tower Competed
Monday, 04 November 2024 18:38
The Sun Tower's shadow marks the passing of the seasons
credit Jonathan Leijonhufvud
For two years News Atlas (https://newatlas.com/architecture/) has reported on the progress of the construction of the Sun Tower in Yantai, China. The 164-foot (50m) curved conical tower was designed by OPEN Architecture symbolized the watch towers of the Ming dynasty (1368 to 1644 CE)...
Hamilton Dial Restoration
Monday, 04 November 2024 17:30
NASS Registered Sundial #1109 at https://sundials.org/index.php/sundial-registry/onedial/1109 is one of a series of bronze sundials presented by Daughters of Union Veterans of the Civil War, dedicated to the memory of the Grand Army of the Republic. Unfortunately the dial in Hamilton, Ohio, suffers from neglect and the gnomon has long been missing.
With support, this dial has been designated...
New Insights into Ancient Sundials
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Larisa N. Vodolazhskaya of the Department of Space Physics at Southern Federal University (SFU), Rostov, has brought two ancient time keepers together with a new and startling result. The story starts at the turn of the end of the 19th century with the discovery of an L-shaped bar found in the tomb of Thutmose III (1479-1425 BCE). that appeared to be a sundial. In the 1930's a "user manual" of sort was found carved on the tomb ceiling of Seti I (1290-1279 BCE) at Abydos. The ideal L-shaped bar had lines engraved with distances from a starting mark of 3, 6, 9, and 12 units. The Seti I text describes these spacings as "an established procedure". But what is the procedure?
al-Biruni's Cosmos
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Al-Biruni's diagram of the moon's phases.
Credit: photo reproduction from Seyyed Hossein Nasr, Islamic Social Science: An Illustrated Study (World of Islam Festival Publishing Co., 1976).
Photo use for non-profit educational purposes only.
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Ibn al-Shatir, whom we give credit for inventing the first modern sundial with gnomon pointing to the celestial pole in 1371 C.E., is but one of many scientific scholars of Central Asia during the “Eastern Renaissance” that lasted from about 800 to 1500 C.E. In this week’s issue of Science, [20 June 2014] Richard Stone reviews the accomplishments of Abu Rayhan al-Biruni (born 973 C.E.) and the possibility that he "discovered" the American continent.
Situated at the crossroads of cultures from China, India, the Middle East, and Europe, al-Biruni was an acomplished astronomer at an early age. At 16 he measured the height of the midday sun and calculated the latitude of his hometown, now in present day Khiva, Uzbekistan.
13th Century BCE Ancient Egyptian Sundial Discovered
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[photo Courtesy University of Basel]
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Professor Dr. Susanne Bickel and her archeological team from the University of Basel found one of the oldest sundials in the world during this year’s excavation in the Valley of the Kings. A limestone sundial was found near tomb KV61 during a survey of the surface rubble. The location of the dial corresponds to an area where there are remains of workmen’s huts dating to the Ramesside Period of the 13th century BCE.
The dial was most likely a vertical, south facing sundial. The horizon line of the dial is about 16 cm across with a hole at the mid point to hold a simple horizontal metal rod or wood stick gnomon, indicating that the gnomon displayed shadows of temporal (seasonally uneven) hours. The limestone dial has a black painted semicircle. On each side of the vertical noon line are 6 segments of about 15 degrees each, representing morning and afternoon temporal (seasonally uneven) hours. Small dots in the middle of each hourly segment serve for even finer timing. Nevertheless, the hour lines are not drawn with precision.
Read more: 13th Century BCE Ancient Egyptian Sundial Discovered
al-Shatir Sundial Technology Challenge of 1371
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At 3pm on August 15th Roger Bailey of the North American Sundial Society will hold a public lecture on the historic Ibn al-Shatir sundial at the Great Falls Library in VA. The Analemma Society proposes to recreate the dial’s design, adapted for the latitude of Observatory Park, The Turner Farm, in Great Falls, VA.
Hopefully this will be the second major dial at Observatory Park maintained by the Analemma Society in conjunction with the Fairfax County Park Authority. The first dial was a commemorative dial designed and built by Tony Moss for the 400th anniversary of Jamestown, VA.
“High on the minaret of the Great Mosque in Damascus is a remarkable sundial created by Ibn al-Shatir in 1371. Through the 10th to 14th centuries the science of astronomy, timekeeping and sundials had advanced in major Moslem centres like Cairo and Damascus. Based on the developing science of timekeeping, Ibn al-Shatir designed a unique instrument that was a breakthrough…The sundial features equal hours rather than the previous system of dividing the day into 12 hours regardless of the seasonal changes.”
Gardom's Edge Monolith
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Gardom Edge Monolith
[photo courtesy of Dan Brown, Nottingham Trent University]
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A two meter standing stone at Gardom’s Edge may be an astronomically aligned monolith set up during the Neolithic period 2,500 – 1,500 BCE to recognize the summer solstice. According to Dan Brown, Andy Alder and Elizabeth Bemand of Nottingham Trent University, “Such an astronomically aligned stone could be described as a seasonal sundial … However it is not intending to mark local time during a day or measure exact dates during a year. Rather the seasonal shadow casting allows for the display of cosmological knowledge such as the ‘death’ and ‘rebirth’ of the Sun”…
The upward facing north slope of the stone remains in shadow until near the time of Summer solstice. Today the stone points south at an upward tilt of 58.3° +/- 2.9°, seemingly aimed at the highest rise of the summer sun, computed for the Gardom Edge latitude of 53.26° as 60.7° in Neolithic times.
Pantheon Sundial
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One of the most iconic buildings in the world, the Pantheon in Rome is an enduring testament to the power and glory of ancient Rome. At the same time, it has also always posed something of a mystery. The only source of natural lighting is a thirty-foot diameter hole at the very top of the hemispherical dome, often referred to as the "oculus".
Working since 2009, scholars Guilio Magli and Robert Hannah discovered that at midday on the equinoxes, a shaft of circular light shines through the oculus and illuminates the Pantheon's entrance.
Early Astronomers
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![]() [photo credit: Andrew Caswell and
Robert Cockburn of The Daily Telegraph ]
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Ask a person what is the earliest evidence of humans building structures to mark significant celestial events, and one offer "Stonehenge". But there may be a structure built thousands of years early according to some experts in Australia.
A site "down under", name Wurdi Youang, estimated to be older than 10,000 years, has a strange arrangement of stones with alignments toward solstices and equinox that has been scrutinized by several eminent Australian scientists. They conclude that the placement and alignment of the stones is not an accident and there is a perfect alignment with the setting sun on the mid-summer day. Understandably, the exact location of the site is a well-guarded secret, but it is known to be west of Melbourne approximately 80 kilometers.
Prosciutto di Portici Sundial's Owner
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Prosciutto di Portici (Ham) Sundial
Photo: Getty Images
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The Prosciutto di Portici Sundial, more often called the Portici Ham Sundial, dates from the first century somewhere between 8 BCE to 79 CE. This small silvered bronze dial was uncovered on 11 June, 1755 in the ruins of Herculaneum (current day Portici) in the "Villa of the Papyri", buried in volcanic ash and charred papyri from the eruption of Mount Vesuvius in 79 CE. The form of the sundial, which resembles a ham, has been extensively studied. It is an altitude dial with similarities to the cylindrical sundial.
Live Science reporter Kristina Killgrove writes, "Historians have long assumed that the owner of the Villa of the Papyri was L. Calpurnius Piso Caesoninus, the father-in-law of Julius Caesar." https://www.livescience.com/archaeology/romans/prosciutto-di-portici-a-portable-sundial-that-looks-like-a-pork-leg-and-it-was-likely-owned-by-julius-caesars-father-in-law-before-mount-vesuvius-erupted
Calpurnius likely commissioned the Epicurean philospher Philodemus to drave the numerous charred scrolls at Villa of the Papyri. Killgrove commented that "This may explain why the Roman pocketwatch was shaped like a ham. For adherents of Epicurean thought, the lowly pig was often used as a metaphor, as it was seen as a naturally pleasure-seeking creature.
To clarify the use of the dial and the drawn lines attributed in the article as "hours before or after sunset" were actually temporal hours. The lines measuried the hours from sunrise to sunset. Temporary (ancient) hours go across the dial face and vertical lines represent the boundary between the zodiac signs representing the twelve months of the year. In this dial the twelve months have been “folded” and the month pair labeled between the lines: IUN-IU (June-July), MA-AU (May-August), AP-SE (April-September), MA-OC (March-October), FE-NO (February-November) and JA-DE (January-December). Notice that both July and August are used and the longest shadows occuring at the end of June while the shortest occur at the end of December. Further, since July and August are named, the dial was created after the reign of Julius and Augustus Caesar, and in particular when Augustus renamed the month Sextilis to August in 8 BCE.
The Ham dial has a fixed gnomon, the flattened piece at middle-left in the photo. When properly working, the gnomon is actually much longer and the tip set a specific distance above the dial face and at the upper left corner of the hour-date lines. To read the time, the dial is rotated from a string at top of the dial until the shadow falls on the vertical date line (or distance between) corresponding to the date. Like the cylindrical sundial, time is read from the downward shadow of the tip crossing the temporary hour line.
The Ham dial also has “folded” hour lines that run across the dial to tell temporary (ancient) hours. The lines are from top to bottom are for sunrise, 1st/11th, 2nd/10th, 3rd/9th, 4th/8th, 5th/7th, and at bottom, the 6th hour line for mid-day.
Historic Sundials of Andalusia
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Esteban Martínez Almirón has published a new book Historical Sundials: Forgotten Andalusian Treasures (Relojes de Sol Históricos Tesoros Andaluces Olvidados) In it he reviews over 400 sundials from the Andalucian region of southern Spain Originally to celebrate the 25th year of the website https://relojandalusi.org/
Esteban Martínez Almirón began showing his sundial drawings on the site. Ultimately more than 60 drawings are in his book, and many are posted on the @stbnart Instagram site. He presents the historical sundials using the themes according to geographical location and building type (e.g. on farms or country houses for daily time telling; churches, cathedrals and other sanctuaries; and civil buildings and public places). Unfortunately many dials have been lost to history and no longer exist.
Martínez Almirón looks briefly at portable sundials of Andalusia, particularly in Sierra de Huelva, the city of Ubeda (where its Renaissance sundials stand out) and the dials of the "New Populations" ("Nuevas Poblaciones"). The book is self-published. If you are interested in purchasing a copy, you can visit https://relojandalusi.org/relojes-de-sol-historicos/. The book cost is 12 euros plus shipping. Text in Spanish.
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