Free Astronomy Magazine July-August 2026

JULY-AUGUST 2026 V isual diagram of the January 2024 stellar occultation by 2002 XV 93 . [K. Arimatsu et al.] TNO 2002 XV 93 has an atmosphere but shouldn’t I n the cold reaches of the outer Solar System lie thousands of small objects known as trans-Nep- tunian objects (TNOs) because they lie outside the orbit of Neptune. A thin atmosphere has been observed around Pluto, the most famous TNO, but studies of other TNOs have yielded negative results. Most TNOs are so cold, and their surface gravity so weak, that they are not expected to retain atmospheres. by National Astronomical Observatory of Japan O rbit dia- gram of trans-Neptunian object 2002 XV 93 (white) with planets shown. The grid repre- sents the eclip- tic plane (plane of Earth’s orbit) and the vertical gray lines out- lining 2002 XV 93 ’s orbit rep- resent the orbit’s vertical distance above or below the ecliptic. [JPL/ NASA/Caltech]