Free Astronomy Magazine November-December 2026

50 ASTRO PUBLISHING NOVEMBER-DECEMBER 2026 Far-out Solar System objects ‘remember’ past by NASA/ESA/CSA Claire Andreoli Ann Jenkins Christine Pulliam F or the first time, scientists used the joint power of NASA’s Hub- ble and James Webb Space Tel- escopes to study some of the most far-flung bodies in our solar system, Trans-Neptunian Objects (TNOs). Some of these are the smallest and faintest ever directly seen. The re- searchers unexpectedly found fewer small TNOs than they expected, and that the colors of these bodies fol- lowed the same relationships as their larger family members. These objects are typically small, faint, icy bodies orbiting the Sun be- yond the orbit of Neptune. Most are more than 100 million times dimmer than objects visible to the unaided eye. In two complementary papers T his artist’s concept depicts a Trans-Neptunian Object (TNO), a small, faint, icy body orbiting the Sun beyond the orbit of Neptune. Often more than 100 million times dimmer than objects visible to the unaided eye, TNOs are so small that even with NASA’s Hubble and Webb space telescopes, they appear only as tiny points of light. [NASA, ESA, Leah Hustak (STScI)] published in The Astronomical Jour- nal , teams analyzed the color, com- position, and size distribution of 27 newly discovered tiny, dim TNOs. This class of small bodies offers the best view into an early stage of planet-building, when a disk of dust and pebbles in orbit around the Sun coalesced into city-sized “planetesi- mals” — the solid building blocks that clump together to form planets — but had not yet merged into full- sized worlds. Beyond Neptune, this second stage never happened, leav- ing behind a frozen population of planetesimals. In the deepest TNO survey to date, teams led by PhD candidates from the University of Victoria in Canada, under the guidance of the National Research Council of Canada, and Northern Arizona University in Flagstaff examined a patch of sky si- multaneously with Hubble, observ- ing the TNOs’ visible light, and Webb, observing their infrared light.