There's something intrinsic to human nature that revels in discovery. Buried deep inside us is that urge to climb a mountain just to see what's on the other side. This instinct lies at the core of science, since science begins with the practice of observation. It's when something stands out from the ordinary that the clues of reality appear, and provided one is in the proper psychological perspective for novelty (a.k.a. "open-minded") the best reward for the curious is often something completely unexpected.

For as long as there have been campfires under starry skies there have also been those with eyes swept up to the heavens. The sharper among them soon noted the "wanderers" that strode aloof among the "fixed" celestial firmament, and the generations that followed named these "planets" with divine significance and learned to predict their paths with greater and greater accuracy. Our generation has at last achieved the mathematical precision and mechanical prowess to launch robotic emissaries to visit them, not only by reaching their own orbital influence but also sensing inhospitable atmospheres and touching barren surfaces. In time God willing we ourselves will follow, but for now our technological senses serve to sate our appetite for exploring neighboring worlds.

This week space lovers were rewarded with a gift for their persistence, packaged in a spectacular series of photos sent back by NASA's Messenger probe, now a little more than four years into its loopy, seven-year spiral in towards Mercury. (The distension comes from using the gravity of this fleeting inner planet to brake Messenger's path piecemeal, somewhat like a child slowing a rotating playground carousel by intermittently dragging their feet in the dirt.) What makes these photos so special is that they expose large portions of Mercury never before seen by humans. Astronomers and scientists must be ecstatic with this new subset of the surface, busy perusing the data for even more surprises. They've already found water high in its exosphere, so there's just no telling what wonders remain to be revealed after studying the amazing features provided by this one brief pass.

Speeding by far too quickly to be captured in Mercury's orbit, Messenger now heads back into sunlit space. Without unexpected interference (a collision with Tan Ru?) it should return once more next year for a penultimate pass before its final approach to orbit in roughly three years. At that point sky watchers everywhere will share a thrill of discovery that tickles us straight to the core. These are indeed days to live for.