Hubble and Webb Telescopes Discover 27 Tiny Trans-Neptunian Objects, Challenging Evolutionary Models
In a joint deep-space observation campaign conducted on September 8, 2026, the Hubble Space Telescope and the James Webb Space Telescope identified 27 previously unknown trans-Neptunian objects (TNOs) beyond Neptune’s orbit, all measuring less than 40 kilometers in diameter, with the smallest being only about 10 kilometers across. The research was led by doctoral students from Northern Arizona University and the University of Victoria.
A striking finding of the study is that regardless of whether these TNOs belong to the dynamically “cold” or “hot” classification, their surface compositions remain highly primitive and well-preserved. This suggests that collisional disturbances in the distant outer regions of the solar system have been far less intense than scientists had previously assumed.
Using the James Webb Space Telescope’s infrared data, the team was able to precisely determine the size distribution of these small bodies. The results indicate that the number of extremely small objects is lower than what existing theoretical models predict, a discrepancy that may prompt a reevaluation of current understanding of the Kuiper Belt’s population.
The findings, published in The Astronomical Journal, reveal a remarkable universality in the processes of planetesimal formation during the early history of the solar system. According to the researchers, the pristine surfaces of these tiny TNOs offer a rare window into the conditions that prevailed when the solar system was first taking shape, before the planets had fully formed.
The collaboration between Hubble’s sensitive optical imaging and Webb’s powerful infrared capabilities proved essential for detecting and characterizing such faint, diminutive objects at the far reaches of the solar system. The study highlights how next-generation space observatories are transforming our ability to probe the outer solar system’s smallest denizens, shedding new light on the origins and evolution of planetary building blocks.
