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Bright idea: pictures of the Mars sundial will be broadcast over the Internet from 2002. Credit: CORNELL UNIV

A Mars Sundial, about the size of a computer floppy disk, will be fixed to the Mars Surveyor 2001 lander due to touch down on the red planet in January 2002.

Viewers on Earth will be able to tell Martian time by tuning into pictures of the sundial taken by the Surveyor's panoramic camera and broadcast over the Internet.

Aside from its public relations value, the sundial will be used to calibrate the lander's colour camera. The idea came from Bill Nye, who as ‘Bill Nye the Science Guy’ hosts a popular children's science show on US public television.

Nye used children's design suggestions and enlisted the help of experts. These included Woodruff Sullivan, an astronomer and sundial expert at the University of Washington, and artist Jon Lomberg, who had a hand in the creation of the Voyager record sent into interstellar space with the Voyager 1 and 2 spacecraft in 1979.

Around the sundial's base is engraved a Voyager-like message that reads in part: “We sent this craft in peace to learn about Mars' past and about our future. To those who visit here, we wish a safe journey and the joy of discovery.”