You're the first spacecraft ever to descend to Titan -- what do you see? Immediately after the Huygen's probe pierced the cloud deck of Saturn's moon Titan last January, it took a unique series of pictures of one of the Solar System's most mysterious moon's.

In 1655, three hundred fifty years ago on this date, Dutch astronomer Christiaan Huygens discovered Luna Saturni - now known as Saturn's moon Titan. To celebrate, consider this intriguing picture of his telescope lens, all that remains of the instrument he used, designed and constructed in collaboration with his brother, Constantijn Huygens.