Sun & planets · Space Codex
Uranus
Tilted 97.8°, Uranus rolls around the Sun on its side, giving each pole about 42 years of continuous daylight.
Ice giant tipped on its side
At a glance
Key points
It has the coldest atmosphere measured on any planet.
- Rolls around the Sun on its side (97.8° tilt)
- Coldest planetary atmosphere measured: 49 K
- Its day was re-measured in 2025: 17 h 14 min 52 s
Interior
More than 80% of Uranus's mass is a hot, dense fluid of water, methane and ammonia above a small rocky core, where temperatures approach 5,000 °C. Unlike the other giants, Uranus releases almost no internal heat, one reason its upper atmosphere is the coldest of any planet.
Atmosphere and seasons
Methane absorbs red light and gives the planet its pale cyan colour. Because of the tilt, each pole spends about 42 years in sunlight followed by 42 years of darkness, and the atmosphere responds with slow, dramatic seasonal changes.
Rings and moons
Thirteen narrow, dark rings circle the planet. Its five major moons, Miranda, Ariel, Umbriel, Titania and Oberon, are named, like most Uranian moons, after characters from Shakespeare and Alexander Pope.
Exploration
Voyager 2's flyby in January 1986 is still the only visit. A Uranus orbiter and probe was the top flagship priority of the 2023 US planetary decadal survey but has not been approved as a mission.
What we still don't know
What knocked Uranus over, why it emits so little heat, and whether any of its large moons hides an ocean.
Moons
The 5 major moons of Uranus in the Codex, each with its own sourced entry.
Missions
- 1977–
The only spacecraft to visit Uranus (1986) and Neptune (1989); interstellar since 5 Nov 2018.
First-hand · our 3D model
How we render it
Uranus is tilted 97.8°, so it rolls along its orbit on its side, and everything follows that tilt: its narrow rings and its five major moons orbit in the tilted equatorial plane. The rings are drawn as five thin bands, with the outermost epsilon ring the brightest. A deep Rayleigh-blue haze shell sits over the methane cloud deck, and the globe is slightly flattened (polar radius 0.977 of equatorial).
Sizes and distances in the model are not to scale, so every world can be seen up close. Colour maps are derived from NASA mission imagery via Solar System Scope (CC BY 4.0). The first frame uses light startup maps; higher-resolution maps stream in after the scene is on screen, decoded off the main thread so the page stays responsive.
Related entries
Sources
- JPL Solar System Dynamics: planetary physical parameters (opens in a new tab)
- NASA Science: Hubble measures Uranus's rotation (opens in a new tab)
- NASA NSSDC Planetary Fact Sheet (opens in a new tab)
- NASA NSSDC Uranus Fact Sheet (opens in a new tab)
- NASA Science: Uranus facts (opens in a new tab)
- NASA Science: Uranus moons (opens in a new tab)
Last reviewed against these sources. Built from public NASA, ESA and JPL data; not affiliated with or endorsed by any agency.