Mounted on top of the rover is probably the last thing you'd expect: a sundial! It's not to tell time, but color
. Taking color pictures isn't all that easy; you have to know a lot about the way the camera works as well as lighting conditions. Things are very different on Mars, so the sundial
has color stripes on it - red, blue, green, and yellow - to help calibrate the cameras. The gnomon - the part of the sundial that casts the shadow - is needed so that scientists back home on Earth can see how lighting changes from full illumination to shadow.
The sundial is inscribed with the words, "Mars 2012 - To Mars - To Explore", and has the word "Mars" written around it in 16 different languages. Image credit: NASA/JPL-Caltech/Malin Space Science Systems