2022 Kuiper Prize Lecture: From Pinpoints of Light to Geologic Worlds: The Magic of Photometry

Robotic exploration of the Solar System revealed one planet, moon, or small body after another as unique geologic worlds. Simultaneously, photometric modeling arose as a complementary field that described both the macroscopic and microscopic features of the surface, including roughness (often at scales below the resolution limit of instruments), compaction states, and the sizes of particles comprising the upper regolith. This “hypervision” positioned photometric analysis with an uncanny ability to claim priority in a number of foundational discoveries, including the prediction that Uranus possessed a family of outer irregular moons, that Titan possessed two major categories of landforms defined by their roughness, that Enceladus was geologically active, that seasonal volatile transport was occurring in the outer Solar System, and that the low-albedo side of Iapetus was exogenously placed. Hints of discoveries yet to come include active cryovolcanism on Europa, a geologically active (136199) Eris, and a small or non-existent polar cap on Triton.