3,4,6,7,- 1Institute for Space Science and Technologies in Asturias, Universidad de Oviedo, Spain (npinilla@uniovi.es)
- 2University of Central Florida, Department of Physics, Orlando, FL, USA
- 3Université Paris-Saclay, CNRS, Institut d’Astrophysique Spatiale, Orsay, France
- 4Space Telescope Science Institute, Baltimore, MD, USA;
- 5Association of Universities for Research in Astronomy, Washington, DC, USA
- 6Jet Propulsion Laboratory, Pasadena, CA, USA
- 7NASA Goddard Space Flight Center, Greenbelt, MD, USA
- *A full list of authors appears at the end of the abstract
The launch of the James Webb Space Telescope (JWST) marked the beginning of a new era in the understanding of our solar system and of planetary systems around other stars, whether they are mature or still in the process of formation. With its unprecedented sensitivity in the infrared, JWST’s spectroscopic instruments have proven to be uniquely suited for identifying and characterizing the fundamental ingredients required to form icy worlds—both those orbiting the giant planets in our solar system and the vast, distant population of trans-Neptunian objects (TNOs), which are believed to be the source of most short-period comets.
In its first year of operations, JWST has delivered the most comprehensive and homogeneous collection of spectra of TNOs to date, thanks to two key programs: DiSCo (Discovering the Surface Composition of TNOs Pinilla-Alonso et al. 2025, Licandro et al. 2025, Brunetto et al. 2025, Henault et al. 2024, De Pra et al. 2025) and the GTO-KBO program (Emery et al. 2024, Grundy et al. 2024, Glein et al. 2024, Pinilla-Alonso et al. 2024). These spectra span a wide range of object types—from small, apparently inactive Centaurs to the larger, cometary-like ones like Chiron, and from small (~100 km) TNOs to the largest known dwarf planets (Eris, Makemake, Haumea). The study of this dataset, combined with results from other targeted programs in cycles 2 to 4, reveals that the current surface composition of TNOs largely reflects the primordial materials that formed planetesimals before the dynamical dispersal of the trans-Neptunian region. Among these materials, three ices, coexisting with silicates and complex organic matter, emerge as the most influential in shaping the surface chemistry of TNOs: water ice, carbon dioxide ice, and methanol.
Furthermore, JWST observations are helping to disentangle long-standing questions about the colors of TNOs observed in visible-light photometry. The spectral evidence now indicates that these colors are more closely influenced to refractory materials—such as silicates and complex organic compounds—than to the presence or absence of surface ices. Importantly, these refractory components are not uniformly distributed across the TNO population, pointing to complex histories of thermal processing, irradiation, and surface renewal.
These discoveries also resonate beyond our solar system. JWST has begun to unveil the mineral and volatile composition of exoplanetary systems, including the detection of silicate clouds in hot-Jupiter atmospheres and the presence of ices and complex organics in debris and protoplanetary disks. By comparing the early building blocks of icy bodies in our solar system to the materials observed in other planetary systems, we gain crucial insight into the universality—or uniqueness—of the processes that led to planet formation.
In this context, the James Webb Space Telescope has also provided groundbreaking evidence of frozen water in the debris disk surrounding the young star HD 181327, located 155 light-years away (Chen et al. 2025). Researchers have recently confirmed the presence of crystalline water ice within this disk, directly linking the formation of icy bodies to the broader processes of planetary system evolution. This crystalline ice, also found in our Solar System’s Kuiper Belt and Saturn’s rings, exists alongside fine dust particles, forming tiny “dirty snowballs.” Webb’s sensitive instruments detected over 20% water ice in the outer regions of the debris disk, confirming the vital role of water ice in shaping the chemical environment of young planetary systems. The detection of water ice in these disks is essential for understanding the formation of gas giants and the delivery of volatiles, like water, to rocky planets, thus providing a deeper understanding of planetary evolution both within and beyond our own solar system.
In this talk, we will highlight the most significant JWST findings related to the solar system, particularly TNOs, and discuss how these results complement and inform our understanding of planetary formation and evolution in extrasolar systems.
References
Grundy et al. 2024 Icarus, Volume 411, article id. 115923
Glein et al. 2024, Icarus, Volume 412, article id. 115999
Emery et al. 2024 Icarus, Volume 414, article id. 116017
Pinilla-Alonso et al. 2024, Astronomy & Astrophysics, Volume 692, id.L11
Pinilla-Alonso et al. 2025, Nature Astronomy, Volume 9, p. 230-244
Licandro et al. 2025, Nature Astronomy, Volume 9, p. 245-251
De Prá et al. 2025, Nature Astronomy, Volume 9, p. 252-261
Henault et al. 2025, Astronomy & Astrophysics, Volume 694, id.A126
Brunetto et al. 2025, The Astrophysical Journal Letters, Volume 982, Issue 1, id.L8
Chen et al. 2025, Nature accepted (Publication date May 15 2025)
And the many members of the DiSCo and GTO-KBO teams
How to cite: Pinilla-Alonso, N., Brunetto, R., Stansberry, J., Holler, B., Hammel, H., Lunine, J. I., Hines, D. C., and Milam, S. and the DiSCo & GTO-KBO Teams: JWST marks a new era in the exploration of ices and dust in our Solar System and beyond, EPSC-DPS Joint Meeting 2025, Helsinki, Finland, 7–12 Sep 2025, EPSC-DPS2025-1796, https://doi.org/10.5194/epsc-dps2025-1796, 2025.
