Probing the Early Solar System with Comet
by
Tsung-Dao Lee Institute/S4F-SW - Open Area
Tsung-Dao Lee Institute
Host: Dong Lai
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Abstract:
Comets are among the most primitive remnants of Solar System formation and preserve invaluable records of the physical and chemical conditions in the early Solar System. Over the past decades, advances in spacecraft exploration and ground-based observations have transformed our understanding of cometary nuclei and their evolution. In this talk, I will review recent progress in comet science, highlighting key discoveries from ESA's Rosetta mission—the first mission to escort a comet through its perihelion passage. Analysis of Rosetta observations has revealed the remarkable diversity of cometary activity and the complex mechanisms driving dust ejection and surface evolution. Building on these insights, I will present recent advances in AI-enabled thermophysical modeling of cometary nuclei. Combining deep learning with decades of SOHO/SWAN water production measurements, we derived nucleus sizes for a large sample of comets. The results suggest that long-period comets are systematically larger than previously inferred, leading to an Oort Cloud-to-Scattered Disk population ratio approaching 103, far exceeding predictions of classical giant-planet migration models. Together with recent studies of stellar flybys in the Sun's birth cluster, these findings point to a more dynamically active early Solar System and illustrate how spacecraft exploration, long-term observations, and artificial intelligence are reshaping our understanding of planetary system formation.
Biography:
Dr. Xian Shi (Shanghai Astronomical Observatory, CAS) received her Ph.D. from the Shanghai Astronomical Observatory in 2012. From 2012 to 2021, she conducted postdoctoral research at DLR and MPS, Germany. In 2021, she joined the Shanghai Astronomical Observatory and established the research group "Exploration and Investigation of Solar System's Small Bodies". Her research focuses on the origin and evolution of small bodies in the Solar System, as well as the scientific analysis of space exploration missions. In recognition of her contributions to understanding the mechanisms of cometary activity, asteroid (33288) Shixian was named in her honor.
