Today's Mars Photo was taken by Viking I shortly after landing on July 20 1976. It was the first photo ever taken from the Martian surface. When we compare this image to a more modern photo of Mars like this one, it is amazing how far our technology has come. Could you imagine getting photos from Mars Exploration Rover Opportunity that looked like this? How disappointing would that be?
The image here is as large as the original, so I have linked it to the NASA's informative page on the image.