HUBBLE AND WEBB TELESCOPES STUDY DISTANT SOLAR SYSTEM OBJECTS

Scientists used NASA's Hubble and James Webb Space Telescopes together for the first time to study trans-Neptunian objects (TNOs), some of the most distant bodies in the solar system. Teams analysed 27 newly discovered TNOs, some among the smallest and faintest ever directly observed. The research, published Tuesday in The Astronomical Journal across two complementary papers, found fewer small TNOs than predicted and discovered that the colours of these bodies matched the same relationships seen in larger TNOs. Most TNOs are more than 100 million times dimmer than objects visible to the naked eye.

Teams led by PhD candidates from the University of Victoria in Canada and Northern Arizona University in Flagstaff, under guidance from the National Research Council of Canada, conducted the deepest TNO survey to date. The coordinated observation used Hubble to observe visible light and Webb to observe infrared light from a single patch of sky simultaneously. The researchers measured the objects' colours—described as fingerprints of surface composition—alongside their sizes and orbital paths. The study examined two distinct TNO types: "cold" TNOs on their original, relatively circular orbits around the sun in the solar system's plane, and "hot" TNOs that formed between Uranus and Neptune before being pushed outward when the outer gas giants migrated early in solar system history.

These small bodies provide insight into an early stage of planet formation, when dust and pebbles coalesced into city-sized planetesimals that later merged to form planets. Beyond Neptune, this second merger stage never occurred, leaving behind a frozen population of planetesimals. The findings offer scientists their clearest view yet of planetary formation processes that shaped the solar system billions of years ago.