Mars Sundial to Help Teach Kids About Time, Sun

John Roach
for National Geographic News

December 9, 2003

If all goes according to plan this coming January, the twin Spirit and Opportunity rovers will land on Mars. At that same time continuously updated images of sundials built by school children and individuals around the world will launch on the Internet.

The link between the two lies in science and the sun.

The rovers are on a months-long quest to understand the history of water on the red planet, a key ingredient for past—or present—Martian life. They'll cruise around the planet, probing and imaging rocks and soils for liquid clues. They also carry the first sundials ever placed on another world.

The Web site project, called EarthDial [see link at the bottom of this story], aims to give humans a sense of how the sun's passage across the sky controls time around the world. The design of all the dials on Earth ties in with the dials on Mars.

"It grows out of the MarsDial project that was taking a science instrument on a spacecraft on its way to Mars," said Woodruff Sullivan, an astronomy professor and sundial expert at the University of Washington in Seattle.

The Spirit and Opportunity rovers are based in part on designs for the scuttled Mars Surveyor 2001 Lander. In examining plans for that mission, Seattle, Washington-based television personality Bill Nye, "the science guy," noted that a small square and post mounted on the rover's deck to calibrate images relayed back to Earth could double as a sundial.

Project scientists at Cornell University in Ithaca, New York, loved Nye's idea and together with the help of Sullivan they designed the first sundial destined for another planet. The sundial was inscribed with the motto "Two Worlds, One Sun."

The Mars Surveyor 2001 Lander mission was cancelled after the loss of the Mars Polar Lander in 1999, but the motto-inscribed sundials made it onto the Spirit and Opportunity rovers currently en route to Mars.

During the time gap between the original and current missions, Sullivan and Nye in collaboration with the Pasadena, California-based Planetary Society hatched the EarthDial project, which aims to have school children and individuals around the world construct sundials similar to the one on the Mars rovers.

"The EarthDial project presents an elegant way to teach students and the general public about a variety of aspects of planetary motion in the deceptively simple sundials," said Bruce Betts, director of projects at The Planetary Society.

Project organizers hope comparisons of the sundials on Earth and Mars will prompt people to ask questions such as: How does time work on Earth? Does the concept of a month make sense on Mars? What should be the name of time units on Mars?

"The idea is for MarsDial and EarthDial to trigger all these questions and be an education vehicle," said Sullivan.

EarthDial Construction

The Planetary Society, Nye, and Sullivan are encouraging school children, community organizations, and individuals around the world to build their own sundials and display them on the Internet using 24-hour webcams.

The organizers hope to post a broad sample of sundials to a single webpage, illustrating the difference in shadows between time zones as well as between the northern and southern hemispheres. As people sweep their eyes across the page, they'll get a sense of time across the globe.

Instructions for how to build an EarthDial are posted to the Web site of The Planetary Society, which will also host the project Web site at least throughout the life of the Spirit and Opportunity missions.

The cost to participants is anticipated to be no more than U.S. $50 for building materials in addition to the cost of acquiring and maintaining a webcam with an around-the-clock Internet connection that refreshes the image regularly.

Each EarthDial will be about 32 inches (81 centimeters) in diameter, or about ten times the size of the MarsDials on the rovers. Like the MarsDials, each EarthDial will have the motto "Two Worlds, One Sun," but in the native language of its owners.

And while the project organizers want the EarthDials to be similar in functionality and appearance, they want individuals to decorate the perimeter of each dial with personal touches and expressions of local culture.

"We want a nice degree of uniformity as you scan across the page so you can be oriented, but we also want some variety," said Sullivan.

Sullivan has already gotten considerable feedback from potential participants in North America, Chile, Holland, Spain, Australia, and even the South Pole. He is hoping that the project will also attract participants from geographically isolated places like the Seychelles in the Indian Ocean.