What's New Under The Sun

Thursday, 28 May 2026 22:31

A wonderful trio of solar eclipses on the Iberian Peninsula will occur.  The first will occur on 12 August 2026 with viewing time of more than 2 minutes. lThe second, almost exactly a year later on 2 August 2027, will be even more spectacular, with an eclipse duration of 4 minutes.  On 26 January 2028 Spain will encounter an annular solar eclipse, creating a view of the rim of the sun...

Thursday, 07 May 2026 20:28

In August, 2009 the NASS Conference was held in Portland, Oregon and visited the sundial at Clark College in Vancouver, WA.  The equatorial sundial, built in 1984, had just received a new gnomon: an analemmatic or "bowling pin" gnomon that corrects for the Equation of Time. On May 4th, 2026 the local newspaper of Clark County, the Columbian, reported that more than 40 years after its...

Tuesday, 21 April 2026 16:47

Heritage Auctions of Dallas, Texas, is auctioning a brass dial signed by "Patrick Hepburn, Marlborough, Maryland, 1720"..  The dial face has a rich green patina with rough but accurate engraving of Roman numeral hours, delineated with half, quarter and eighth hour marks. The dial has an eight point compass rose with lettered points.  Latitude is engraved as "LATT 39".The wide, but...

Sunday, 12 April 2026 21:30

Do you wonder what a Bifilar Sundial is? Or a Campbell-Stokes Recorder? Maybe you are studying facts about astrolabes and come across the word almucantar.  Are they rings in the sky? Our perhaps you want to make a vertical dial and need the trigonometric formula to draw the hour lines and have forgotten where to look.  All of these questions can be answered plus internet and NASS...

Monday, 06 April 2026 01:08

The Times Colonist in an article of March 28, 2026 by Hannah Link, reports that as of November 2026, British Columbia will change to permanent daylight time.  "That means sundials in B.C. will always be one hour behind, no matter the time of year, said Victoria-based sundial enthusiast Steve Lelievre." Photo: Times Colonist - The sun shines on the Sundial Garden in Beacon Hill...

Monday, 09 March 2026 15:10

Building on the success of the 2025 inaugural event celebrating world sundial day on March 20th, 2026. This global online gathering celebrates sundials, timekeeping, astronomy, history, art, mathematics, craftsmanship, and cultural heritage across the world. World Sundial Day was originally created by Esteban Martínez Almirón on his website Reloj Andalusí. World Sundial Day is celebrated...

Thursday, 22 January 2026 18:30

UPDATE:  We will have a special tour of the Kentucky Viet Nam Memorial Sundial.  See the attachment about the construction of this wonderful memorial. Get ready to travel. This year the 31th NASS annual conference will be held in Louisville, KY at the Hyatt Regency Hotel June 25th - June 28th. The conference starts Thursday June 25th at 4:30pm with an opening reception, introductions,...

Monday, 13 October 2025 22:49

On October 4, 2025 Madison Historical Society of Ohio was able to have their sundial returned after 32 years, when in 1993 it was moved to the lawn of Lake County Courthouse to reduce the chance of vandalism. The sundial was originally placed at Madison Home 100 years ago on Saturday, October 24, 1925 during a conference of the Women's Relief Society.  From 1904 to 1962 the state ran this...

Monday, 15 September 2025 19:42

NASS is pleased to announce the upcoming fifth instance of Elements of Dialing, our introductory course about sundials, their history, and the science that makes them work. The free 12-lesson course, intended for those are new to sundialing, runs from 27 October 2025 until 26 April 2026. The course instructor is Robert Kellogg, NASS Vice President and Sundial Registrar.  Bob will be...

Thursday, 11 September 2025 23:11

A Hungarian born American scientist, Mária Telkes (1900-1995), was called "The Sun Queen" and among other honors, was postmousthly inducted into the National Inventors Hall of Fame. She lived to 95 and for most of her life developed solar power in a variety of forms. Trained as a biophysicist, she worked for Westinghouse Electrical and Manufacturing Company in Pittsburgh, PA, where she...

Thursday, 28 August 2025 23:25

The annual NASS Conference was held 7-10 August, 2025 in Ottawa.  As usual, the conference began late Thursday afternoon with an introduction social and a "grab bag give away", taking your chances with tickets to win the bag's prize.  Will Grant was the final winner of the Walton Double Planar Polar Sundial, but Paul Ulbrich beat the statistic odds and won this prize three times,...

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...

Equation of Time

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Even if your dial includes the longitude correction, its timekeeping will vary throughout the year due to a phenomenon called The Equation of Time. Simply put, the apparent motion of the sun compared to your watch will cause your dial to appear as much as 16 minutes" fast" or "slow" at various times of the year.

The Equation of Time is caused by the combination of two effects: (a) by the earth's elliptical orbit where the laws of Kepler tell the earth to speed faster near the sun than away...that is, at perihelion in December the earth's orbital change is faster that during the June aphelion, and (b) the 23.44° tilt of the earth's axis from the elciptic plane of its orbit.

The chart below shows the amount your dial will vary from clock time through the year. Right click on the graph, select save image for copy, and then print it out and keep it close to your dial. There are dials which compensate for the Equation of Time, but they are complicated.

eotgraph