Science & Tech · Space · 5 hrs ago
Models suggest Uranus and Neptune have different chemical histories
Uranus and Neptune are similar in size, but models estimate much more oxygen deep inside Neptune.
Researchers led by Tom Briand used carbon monoxide high in each planet’s atmosphere to estimate the oxygen far below, where water clouds form under extreme pressure.
The method was needed because telescopes can see only the tops of their atmospheres, and no spacecraft has visited either planet since Voyager 2 flew past them in the 1980s.
The model estimates oxygen levels of about 60 to 180 times the Sun’s proportion for Uranus, and 220 to 340 times for Neptune.
Those differences in the planets’ carbon-to-oxygen ratios may point to different formation regions in the disk of gas and ice that surrounded the young Sun.
The estimates depend on how strongly each atmosphere mixes, and the researchers say the planets’ ratio ranges overlap, so a shared value cannot be ruled out.
Models estimate that Neptune has a much higher proportion of oxygen deep in its atmosphere than Uranus.
The researchers say the planets’ differing carbon-to-oxygen ratios may indicate they formed in different parts of the disk that built the solar system.
The model estimates put Uranus’s oxygen at 60 to 180 times the Sun’s proportion, compared with 220 to 340 times for Neptune.
The estimates depend partly on how vigorously each planet’s atmosphere mixes, and the researchers say the two planets’ carbon-to-oxygen ranges overlap.
- Who
- A research team led by Tom Briand of Aix-Marseille Université.
- What
- Models estimate that Neptune has more oxygen deep in its atmosphere than Uranus. The difference may point to distinct formation histories.
- When
- The article was published on November 13, 2026. The study date is Not stated.
- Where
- Uranus and Neptune in the solar system.
- Why
- The team used carbon monoxide in the upper atmospheres to estimate oxygen levels deep inside the planets and compare their carbon-to-oxygen ratios.
This story does not have two clearly opposing sides.
Voyager 2 flew past Uranus.
Voyager 2 flew past Neptune.
Carbon monoxide has been known in Neptune’s atmosphere.
Observations by the ALMA telescope array confirmed carbon monoxide in Uranus’s lower atmosphere.
- Uranus oxygen estimate
- 60 to 180 times the Sun’s proportion
- Neptune oxygen estimate
- 220 to 340 times the Sun’s proportion
- Uranus carbon-to-oxygen ratio
- 0.06 to 0.52
- Neptune carbon-to-oxygen ratio
- 0.02 to 0.12
- Neptune carbon monoxide
- About 0.2 parts per million
- Uranus carbon monoxide
- About 5.6 parts per billion in the team’s reading of 2022 data
What people are saying
Uranus and Neptune may resemble twins today, but their chemistry is telling us that they are more like cousins with very different histories.