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Projects: EarthDialsHistorySundials are ancient objects. For millennia, humans have appreciated that the shadow of a post (also known as a gnomon) could be used to tell time as the Sun travels westward across the sky. The date can also be read from a sundial, for the path of the Sun through the sky is much higher in summer than winter, causing generally shorter shadows in summer. Sundials reached their peak in the 18th century but then rapidly declined as clocks and watches became affordable and accurate (and with the distinct advantage of being able to work under clouds or at night!). Today they are no longer practical for timekeeping, of course, but they are nonetheless still marvelous devices for educational, philosophical, and artistic purposes. A sundial today, when well designed for its users and location, makes one pause from the bustle of modern life and contemplate our history and our position in the cosmos.
Two sundials were sent to Mars aboard the Mars Exploration Rovers. Actually the photometric calibration targets for the Panoramic Camera instruments on the rovers, the MarsDials were the first sundials to be sent to another planet. The MarsDials were designed by an informal team consisting of: Jim Bell, the lead scientist for the Pancams; Bill Nye, the Science Guy; Woody Sullivan, a professor of astronomy at the University of Washington; Louis Friedman, Executive Director of The Planetary Society; Jon Lomberg, a well-known artist specializing in astronomical subjects; and Tyler Nordgren, an astronomer and artist then at the U.S. Naval Observatory and now at the University of Redlands. Sullivan, a self-proclaimed sundial fanatic, had long imagined using the World Wide Web to follow the shadow of the Sun. The impending launch of the MarsDials to Mars created an opportunity for him to accomplish his vision. Together, Sullivan and Nye developed a plan to have sundials all over Earth that were visually reminiscent of the sundials on Mars. Each one would have a Webcam broadcasting the position of its shadow to a website that could be viewed by anyone anywhere in the world. Each EarthDial would have decorations specific to its location. Like the two MarsDials, all EarthDials would carry the motto “Two Worlds - One Sun,” except that the motto would be translated into the local language. Nye and Sullivan asked for The Planetary Society’s help to bring this idea to the rest of the world. The Planetary Society developed step-by-step instructions for EarthDial construction, promoted the EarthDial project to its members around the world, and hosted the EarthDial Website. When the site went live at planetary.org on March 2, 2004, two months after the MarsDials had landed with the rovers on the Red Planet, there were 11 EarthDials online, in the USA, Honduras, Spain, Malaysia, and even in Antarctica at the South Pole (where the Sun was very close to setting entirely for the winter). At the height of the program, the number of EarthDials peaked at 20 in 6 different countries in September 2004. Through the life of the program EarthDials sprang up at 36 different sites in 15 different countries on 6 continents! A few EarthDials are still broadcasting live, and Sullivan, Nye, and The Planetary Society would be delighted to see new ones develop. |
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