Overview
- ALMA observations taken three times between 2022 and 2024 and reported June 19–20, 2026 detected carbon monoxide in Uranus’s lower atmosphere for the first time.
- The lead team compared the measured CO to a set of interior models and found only models with high ice and water content reproduced the observed abundance.
- The same data also show separate CO in the upper atmosphere that the authors attribute to an external source, likely a comet impact centuries ago, and not the deep interior.
- Independent scientists caution that translating an atmospheric CO signal into a firm interior composition depends on uncertain details of chemistry, vertical mixing and internal structure, so the result narrows the debate but does not close it.
- If confirmed, the finding would shift ideas about how Uranus formed and its similarity to Neptune and will prompt further observations and modeling to test the chemical and transport assumptions behind the conclusion.