A tiny world in our Solar System has an atmosphere it shouldn’t—hinting something dramatic happened there recently.

A group of Japanese astronomers, including both professionals and amateur observers, has found signs of a thin atmosphere surrounding a small object far beyond Neptune. The discovery is surprising because the object is so small that it should not be able to hold onto gas for long. This raises new questions about when the atmosphere formed and what is keeping it there. Additional observations will be needed to better understand this unusual finding.

Why most trans-neptunian objects are airless.