Tiny, icy worlds at the edge of the solar system are helping scientists rewind the story of how planets like Earth first came together.These distant, city‑size bodies orbit far beyond Neptune in space and are leftover building materials from the solar system's early days. They have spent billions of years in a deep freeze, preserving clues to how the first solid worlds formed.Until now, astronomers could only study larger members of this population, from dwarf planets like Pluto and its moon Charon down to mid‑size objects such as Arrokoth. The truly tiny ones, only a few miles wide, stayed out of reach.
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In two new studies, scientists used NASA's James Webb Space Telescope to find dozens of these tiny worlds, then followed up with the Hubble Space Telescope to measure the light from their frozen surfaces.Together, the results give astronomers the largest census of these distant objects ever made, showing how many of these tiny worlds exist and what their surfaces are made of. The observations turn a scattered set of icy rocks into a detailed look at how the building blocks of planets formed and how little they have changed. The scientific papers both appear in The Astronomical Journal.
