A penny on Mars, captured in a photo by NASA's Curiosity rover. (Image credit: NASA/JPL-Caltech/MSSS) Can you imagine picking up a lucky penny on Mars ? What is it? NASA's Curiosity rover captured a surprisingly Earthly image on the surface of Mars. With its Mars Hand Lens Imager (MHLI), the rover snapped a close-up image of a penny. (To clarify: The penny wasn't found there by accident; it traveled to Mars with the rover .) Article continues below This image was captured on Oct. 2, 2013 on the 411th sol, or Mars day, of the Curiosity rover's mission on the planet. On the penny's surface, reddish Martian dust has collected over the 14 months that the mission had already been on Mars by that point. Why is it incredible? It's neat to see a penny on another planet. It's a (now endangered) relic from our own world minted over 100 years ago, in 1909, feeling the Martian wind dragging dusty debris across its surface millions of miles away. But this penny serves a surprisingly important purpose: scale.…