A team of astronomers in Japan has detected a thin atmosphere around (612533) 2002 XV93, a trans-Neptunian object about 500 km in diameter — an object far too small and cold to retain one. An artist’s conception of the trans-Neptunian object 2002 XV93. Image credit: NAOJ. “In the cold reaches of the outer Solar System lie thousands of small objects known as trans-Neptunian objects (TNOs) because they lie outside the orbit of Neptune,” said Dr. Ko Arimatsu from Ishigakijima Astronomical Observatory and colleagues. “A thin atmosphere has been observed around Pluto, the most famous TNO, but studies of other TNOs...