MARSEILLE, France, Oct. 20, 2026 - Researchers have found Neptune's deep atmosphere is substantially richer in oxygen than the atmosphere of Uranus, according to new work published this week. ^[1] The team led by Tom Briand of Aix-Marseille University combined observations from the X-ray Imaging and Spectroscopy Mission with international radio and millimetre telescope networks for the analysis. ^[2] The paper appears in the journal Astronomy & Astrophysics. ^[3] Space Nugget. Uranus and Neptune are the solar system's only ice giant planets. They are nearly matched in mass, diameter and distance from the Sun, but have exhibited consistent, unexplained differences in observed atmospheric properties for decades.