Sundials - World's Oldest Clocks

North American Sundial Society

Want to know the exact time of sunrise in 2000? Or Carl Lehrburger's account of an equinox site with a noon hour sundagger formed by fallen rock? Then this site is for you. Uncommon information is provided such as "Old Celtic calendars observed Cross Quarters, approximately midway between each pair of adjacent Equinox and Solstice days. Unlike modern calendars that define the start of a season on a Solstice or Equinox, the Celts perceived Solstices and Equinoxes as events occurring mid-season, with the seasons actually beginning and ending on the Cross Quarters." Interesting bibliography on ancient American petroglyphs and alignments.
Atmospheric Refraction
Ever wonder how atmospheric refraction affects the position of the sun? Especially at sunrise and sunset. This website by Victor Reijs presents a very technical view of atmospheric refraction with empirical as well as formulas for the position of the sun at rise and set. Extensive links to other sites on atmospheric refraction.
Azimuth and Elevation of the Sun,aziele.html
Here is Dr. Daniel Roth’s simple Azimut und Elevation der Sonne calculator based on equations from Pfeger’s Astronomy with the Personal Computer. Simple to use. There are other programs as well, including a calendar for any year, and the date of Easter.
Yvon Masse has created a simple tool for designing sundials. The program called Calcad allows you to simulate and create a sundial oriented in any position, at any angle, without any specialized knowledge. In return, all Yvon wants is a picture of your sundial. The October 2014 version works on Microsoft PCs, Macs and Linux systems. The software also comes in a "portable" version so that it can be carried on a thumb drive and does not have to be installed on the computer itself. Try it out!
Cartesius Sundial Software
Riccardo and Andrea Aselmi have created software design tools to create a wide variety of sundials, including horizontal and vertical declining sundials, cylindrical, conical, bifilar, and other types of sundials. They now offer Cartesius Web 2018, a web based sundial designing software tool.
Czech Sundial Calculator
Need help with sundial design? Miroslav Broz’s Czech Republic site provides a wonderful collection of calculators for sun position, equation of time, and the calculator software itself. You can design horizontal and vertical dials, equatorial dials and more. Miroslav provides a beautiful catalog of Czech Republic sundials designed with his software. Enjoy the art of designing.
Daylight World Map
This program by Steven Pugh is an JAVA applet to show which parts of the globe are in daylight and which are in darkness. The position of the sun (projected on to the Earth) is shown as a yellow circle. Various locations around the world can be selected, and the date and time can be changed. For the currently selected location and the current date and time, information such as the number of daylight hours and sunrise/sunset times are shown in a panel on the right-hand side. A plane or topographic map can be selected. JAVA run time plugin is required for your browser.
Delta CAD
Delta CAD is a favorite computer aided design (dialing) program. First, you can import sundial designs from programs such as de Vries ZW2000, SONNE, and use Delta CAD to add final touches or you can choose from existing "Basic Programs" that direct Delta CAD to draw sundials on its own. Lots of instructional help is available from Carl Sabanski's Sundial Primer
Earth and Moon Viewer
Have you ever wondered what the division between day and night might really look like from space? The Earth and Moon visualizer does exactly that. Created by John Walker, co-founder of Autodesk, a variety of globe and topographic map views are available at the click of a mouse. Clouds? Today's weather? City lights? It's all there at your command. And click on "Details" explains how this all came about and the resources used to assemble these remarkable views.
Excel Analemma Spreadsheet
Want to draw your own analemma? Visit Walter Sanford’s site for a number of links and tools for the sundialist to construct the analemma, that peculiar "8" shaped figure that the sun makes during the year when observed at the same clock time each day. Walter gives clear directions to making you own spreadsheet or download the North American Sundial Society Excel spreadsheet SunAnalemma.xls. There are lots of excellent references to computing and drawing the sun’s analemma, including an indoor project project by Robert Terwilliger.
National Renewable Energy Laboratory
And you though the Department of Energy was only about electricity? The National Renewable Energy Laboratory (NREL) provides a solar calculator with many options: position, declination, sunrise, sunset and much more. Prints a table of data for any start to end date. NREL's Solar Position Algorithm calculates the solar zenith and azimuth angles in the period from the year -2000 to 6000, with uncertainties of +/- 0.0003 degrees based on the date, time, and location on Earth. Further information and actual C-code of the algorithm may be downloaded: Reda, I. and Andreas A. report Solar Position Algorithm for Solar Radiation Applications, NREL Report No. TP-560-34302, Revised January 2008
NOAA Solar Calculator
The National Oceanic and Atmospheric agency (NOAA) provides sunrise-sunset calculator and calculator for solar declination, azimuth, elevation, and equation of time. PDF files are available for low and high accuracy solar position equations as well as sun. There are both "old" and "new" calculators. The old provides tables of data, the new provides a more graphical interface on a world map. NOAA also provides links to other solar calculators.
Orologi Solari e Meridiane
Want software that allows you to draw a variety of gnomonic sundials with a variety of details? Then Orologi Solari e Meridiane is the site for you. Gian Casalegno, an experienced Italian sundialist, offers both software and explanations of sundial construction. Illustrated here is the orologio del pastore, the shepard dial. (To allow easier construction, the gnomon is actually a slit in the top cardboard flange.) Want to draw dials with Babylonian (Hours from Sunrise) or Italian Hours (Hour to Sunset) or Temporal Hours (12 hours in the daylight)? It’s available at the click of a button with Gian’s software.
Photographer's Ephemeris
What happens when you combined Google Maps with a Luni-Solar ephemeris? The answer is The Photographer’s Ephemeris, a wonderful (and free .. but donations accepted) program by photographer and programmer Stephen Trainot. The program is nicely laid out and easy to use. You can use the program to determine sun or moon rise and set against a real landscape of mountains and irregular terrain. And if you climb a mountain, you’ll find that your sunrise occurs just a bit earlier and your sunset just a bit later due to elevation depression. If Ansel Adams had this!
Shadows Pro
Want to create an astrolabe? A planisphere? Or one of a wide variety of sundials? François Blateyron has created a series of software programs suitable for the first time dialist or for experts. A testimonial comes from Jim Tallman of Artisan Sundials: “You may be interested to know that, for the 6th year, I used Shadows to lay out the Sawyer Prize Dial for NASS (North American Sundial Society), a special edition Spectra sundial. There are now 350+ Spectra dials out there under the sun, in 7 countries and about 40 US states. I used Shadows for every one of them. I use Shadows almost every day - I guess that makes me one of your power users! Thank you again for making it and for your ongoing efforts to continually improve it!” Shadows Pro is a very polished software for sundial makers. The entry level software is free of charge, with Expert and Professional level software costing from 20 to 60 €
SONNE - Sundialist's Software
his is the website of Helmut Sonderegger, offering several sophisticated programs for constructing over 20 different dials with "Sonne", a general sundial construction program and "Alemma" devoted to making analemmatic sundials. The programs offer many options for setting lattitude, longitude,gnomon origin, line colors, dial furniture and auxilliary lines, and text options. Once the sundial is constructed, it can be saved in several differnt formats including DXF for etching or machining.
Sun Excel Spreadsheet
On Carl Sabanski's Sundial Primer you can find "SUN", an Excel spreadsheet application developed by dialist Ricardo Cernic. It provides a full solar ephemeris in English, Portuguese, French, Spanish. Provides Italian, Babylonian, and Temporal Hours as well as Local Solar Time and Sidereal Time. Sorry, this spreadsheet requires Windows and will not work on a Mac.
Sun Simulator
Astronomy Education at the University of Nebraska at Lincoln provides a sun simulator showing the motions of the sun. Move the sun by the hour or through the year. Select display of the sun's declination circle, ecliptic, and analemma. The rotating sky lab has an instruction manual for the teacher and pre/post testing. Animations use Macromedia Flash (.swf) files.
Sustainable by Design
Sustainable by Design provides a suite of shareware tools on sustainable energy topics, including sun angle, sun position, and solar path. Good resource for both dialist and architect. Analyze louver shading and window overhang design. Sustainable by Design provides monthly climate, clouds, sun, temperature, and more for over 250 cities throughout the United States. Data is presented succinctly in graphs. Find out how much sunlight your city gets each month!
US Naval Observatory - Solar Position
This USNO site offers simple formulas for computing the position of the sun, with an accuracy is about 1 arcminute within two centuries of the year 2000. Clearly written, it walks the user step by step to compute the sun's geocentric apparent ecliptic longitude and, given the mean obliquity of the ecliptic (tilt of the earth), the right ascension (longitude) and declination (latitude) of the sun. The formulas include the computation of the Equation of time.