PlanetSolar system
Uranus
A pale-blue ice giant that rolls around the Sun on its side, with a family of dark rings and a surprisingly dynamic atmosphere.
- Planet type
- Ice giant
- Mean radius
- 25,362 km
- Distance from the Sun
- 19.2 AU · 2.87 billion km
- Day length
- 17 h 14 min, retrograde
- Orbital period
- 84 Earth years
- Axial tilt
- About 98°
- Cloud-top temperature
- About −195 °C
- Confirmed moons
- 28
An ice giant on its side
Uranus is the seventh planet from the Sun and the third-largest planet by diameter. Its axis is tilted by about 98°, so the planet appears to roll along its orbit. That extreme tilt produces decades-long seasons: one pole can face the Sun continuously for about 42 Earth years while the other remains in darkness.
Its atmosphere is dominated by hydrogen and helium, with methane absorbing red light and giving the planet its pale blue-green color. Beneath the atmosphere, water, ammonia, and methane-rich material forms a hot, dense “ice” layer rather than a solid surface.
A quiet, seasonal atmosphere
Uranus looked almost featureless to Voyager 2 in 1986, but later observations revealed clouds, storms, and seasonal changes. JWST is now resolving the planet’s upper atmosphere and ionosphere in new detail, while stellar occultations reveal the structure of its thin rings and upper haze.
Its ring system is faint and dark, and its 28 known moons include small icy bodies and larger worlds such as Titania and Oberon. The system remains one of the least explored in the Solar System.
A real view of Uranus
NASA/JPL-Caltech · Voyager 2
The next mission
The planetary science community has identified an Uranus Orbiter and Probe as a high priority for the next decade. A dedicated mission would measure the planet’s interior, atmosphere, magnetic field, rings, and moons in ways that flybys cannot.
- What is the interior structure of an ice giant?
- Why is Uranus’s magnetic field so tilted and offset?
- How do its rings and small moons evolve?
- How do the extreme seasons shape its atmosphere?
Recent publications
| Year | Paper | Journal | Link |
|---|---|---|---|
| 2026 | JWST Reveals the Kuiper Belt–like Compositions of the Uranian Rings and Small Moons | ApJ Letters | DOI |
| 2025 | The Ionosphere of Uranus as Revealed by JWST | Geophysical Research Letters | DOI |
| 2024 | Radiative-convective models of the atmospheres of Uranus and Neptune | Astronomy & Astrophysics | DOI |
| 2024 | Uranus’ hydrogen upper atmosphere: Insights from pre- and post-equinox HST Lyman-α images | Astronomy & Astrophysics | DOI |
| 2023 | The Upper Atmosphere of Uranus from Stellar Occultations | Planetary Science Journal | DOI |
Compiled 20 October 2026. Links resolve to the publisher DOI record.