Worlds this small and distant are thought to be too cold and have too little surface gravity to hold onto gases. But the findings suggest that icy, rocky objects in the solar system’s outer reaches are more dynamic than we thought Illustration of a time sequence as the celestial body moves in front of a distant star NAOJ A tiny, icy celestial body farther from the sun than Pluto seems to have something it shouldn’t: an atmosphere. Researchers don’t expect such a minuscule, distant world to cling to gases. So, the findings, described in a study published May 4 in the journal  Nature Astronomy , challenge standard assumptions about these astronomical objects. “This discovery suggests that small icy worlds beyond Neptune may not be as inactive or unchanging as we often assumed,” study co-author  Ko Arimatsu , an astronomer at the National Astronomical Observatory of Japan, tells  Science News ’ Lisa Grossman. The little world in question is called 2002 XV93.…