An icy world, perhaps just 300 miles wide and far beyond Pluto , may have air, challenging the assumption that small space objects can't hold onto an atmosphere . This world, known as 2002 XV93, orbits in a distant region sprinkled with leftover rubble from our solar system's early planet-building days. Astronomers often study this ancient detritus, referred to as Trans-Neptunian Objects , by waiting for remnants to pass in front of stars. During rare alignments, researchers can measure how the starlight changes to learn about an object's size and features, such as rings or debris. What scientists saw instead for this object was startling. On Jan. 10, 2024, the little object eclipsed a faint star — a star so anonymous it doesn't even have a common name. But that event, seen from East Asia, revealed thin air on 2002 XV93. Typically, if an object has no atmosphere, the background starlight disappears abruptly as the object blocks it.…