The Martian rovers Opportunity and Spirit have represented optimism, hope and even cuteness to millions of people dreaming about discoveries on the Red Planet.

How appropriate, then, that the newest rover, Curiosity, should carry a sundial with sentiments and illustrations worthy of classic children’s literature. Curiosity blasted off onboard an Atlas 5 rocket on November 26 and is currently heading for Mars with an August 2012 landing date.

The sundial doubles as the color-calibration target for the Mast camera (Mastcam) that will capture the Martian landscape. Its image will be transmitted from Mars to Earth many times, and students might use it to learn about the ways that such simple but elegant instruments can be used to determine the time, date, season and latitude on a planetary surface with atmospheric hues different from our own. And it will remain on Mars for the benefit of future space travelers.

Among the messages and illustrations on the sundial is the name “Mars” written in 16 different languages, including ancient Sumerian and Inuktitut, around the edges.

The artist behind this creation is Jon Lomberg, who was Carl Sagan’s colleague and favorite artist and who has launched five message artifacts to Mars, with this sundial on Curiosity marking the fifth. Three others have made it, including the DVD he helped to curate entitled Visions of Mars, attached to the 2007 Phoenix lander. You can read more about the sundial on Lomberg’s blog at ­

Like the other rovers before it, maybe one day Curiosity will become the stuff of legend and storybook dreams.