Ice giant

Uranus

Uranus rotates on its side and has an offset magnetic field, making it a priority target for ice-giant physics.

Uranus: loading local 3D asset.

Physics Snapshot

Planet order
7 from the Sun
Planet class
Outer ice giant
Mean distance
19.191 AU
Revolution period
30,688.5 Earth days
Rotation period
17 h 14 m 24 s retrograde
Relative rotation speed
20.882 deg/s display retrograde
Mean temperature
-195 C mean cloud-top temperature
Atmosphere
Ice-giant atmosphere over a deep interior rich in water, ammonia, and methane compounds.
Main gases
Hydrogen and helium dominate; methane absorbs red light and gives the blue-green color.
Surface / cloud pressure
No solid surface; 1-bar atmospheric level is used as a reference.
Ocean status
No surface ocean. Interior models include deep water-ammonia-methane fluids or ionic phases under high pressure.
Perihelion / closest
18.33 AU (2.742 billion km)
Aphelion / farthest
20.11 AU (3.004 billion km)
Orbit ellipse
0.0463
Mean/reference radius
25,362 km
Gravity definition
8.69 m/s²
Escape velocity
21.3 km/s
Day length
17.2 hours
Known moons
29 confirmed
Mission record
Voyager 2 is the only spacecraft to fly by Uranus; future orbiter concepts are a high science priority.

What Scientists Watch

Classification: Outer ice giant. Mercury through Mars are inner rocky worlds; Jupiter through Neptune are outer giants.

  • Its extreme axial tilt creates unusual seasonal forcing.
  • The atmosphere contains methane, which absorbs red light and gives Uranus its blue-green color.
  • A dedicated orbiter would transform knowledge of ice-giant interiors and moons.

Exploration note: Voyager 2 is the only spacecraft to fly by Uranus; future orbiter concepts are a high science priority.

Atmosphere and oceans

Gases, temperature, and liquids

Atmosphere
Ice-giant atmosphere over a deep interior rich in water, ammonia, and methane compounds.
Main gases
Hydrogen and helium dominate; methane absorbs red light and gives the blue-green color.
Pressure
No solid surface; 1-bar atmospheric level is used as a reference.
Surface / cloud temperature
About -195 C near the cloud-level reference region; Uranus has some of the coldest planetary atmospheric temperatures.
Oceans and liquids
No surface ocean. Interior models include deep water-ammonia-methane fluids or ionic phases under high pressure.
Stable surface liquids
No accessible solid surface or liquid ocean surface.

Interpretation note

How to read these values

Rocky worlds list surface conditions directly. Jupiter, Saturn, Uranus, and Neptune do not have hard surfaces, so temperature and pressure are referenced to atmospheric levels such as the 1-bar cloud region.

Ocean status separates the planet itself from its moons. Several outer-planet moons are major ocean-world targets even when the parent planet has no surface ocean.

3D asset view

Rotatable planet model

Uranus: loading local 3D asset.

This viewer loads the local asset-backed model for Uranus and applies the sidereal axis tilt and relative rotation direction for study. Drag to rotate, wheel to zoom, and open full screen for close inspection.

Elevation and relief

Topography map notes

  • Uranus has no solid visible surface relief, so the study map emphasizes subtle methane bands, storms, and a brightened polar cap.
  • Because the spin axis lies nearly in the orbital plane, seasonal illumination geometry is extreme and changes what observers can see over decades.
  • Its narrow rings and tilted magnetic geometry make the whole system feel dynamically off-axis.

Interior and field

Core, mantle, and magnetism

Upper atmosphere
Hydrogen-helium envelope with methane clouds and hazes
Icy mantle
Deep high-pressure water-ammonia-methane fluids or ionic phases
Core
Rocky inner core beneath the volatile-rich mantle

Orbital characteristics

Detailed orbit solution

Epoch
J2000
Perihelion
18.33 AU (2.742 billion km)
Aphelion
20.11 AU (3.004 billion km)
Semi-major axis
19.2184 AU (2.875 billion km)
Eccentricity
0.0463
Sidereal period
30,688.5 Earth days
Synodic period
369.66 Earth days
Average orbital speed
6.80 km/s
Inclination
0.773 deg to the ecliptic
Longitude of ascending node
74.006 deg
Argument of perihelion
96.998 deg

Physical characteristics

Bulk properties and rotation

Mean radius
25,362 km
Flattening
0.02293
Surface area
8.1156 billion km²
Volume
68.33 trillion km³
Mass
8.6810 × 10²⁵ kg
Mean density
1.27 g/cm³
Reference gravity
8.69 m/s²
Escape velocity
21.3 km/s
Sidereal rotation
17 h 14 m 24 s retrograde
Equatorial rotation speed
About 2.59 km/s
Axial tilt
97.77 deg
Geometric albedo
0.488

Atmosphere profile

Pressure, composition, and temperature

Pressure reference
1-bar cloud level
Composition
About 82.5% hydrogen, 15.2% helium, and 2.3% methane in the upper atmosphere
Cloud-top temperature
About -195 C
Color source
Methane absorbs red wavelengths and leaves the blue-green appearance

Field review

Magnetic field, core behavior, and crater context

  • Uranus has a strongly tilted and offset magnetic field rather than a centered dipole aligned with rotation.
  • That geometry suggests the dynamo may operate in a shell within the icy mantle rather than in a deep central core alone.
No cratered atmospheric surface is visibleNorthern polar capMethane band structureNarrow ring system

Moon catalog

Moons Available

Confirmed count: 29 confirmed

Cordelia, Ophelia, Bianca, Cressida, Desdemona, Juliet, Portia, Rosalind, Cupid, Belinda, Perdita, Puck, Mab, Miranda, Ariel, Umbriel, Titania, Oberon, Francisco, Caliban, Stephano, Trinculo, Sycorax, Margaret, Prospero, Setebos, Ferdinand, provisional S/2023 U 1, and provisional S/2025 U 1.

Data note: rotation values are sidereal periods. For solar orbits this guide uses perihelion and aphelion; those are the Sun-orbit equivalents of closest and farthest orbital distance. Gravity is surface or equatorial gravity for rocky planets and a reference-level value for giant planets, so rounded fact sheets may differ slightly. Moon counts can change when new satellites are confirmed.

Data basis

How these values are normalized

Orbital elements are presented in a J2000-style reference format. Rotation values use sidereal periods unless a solar day is explicitly named. For giant planets, pressure, temperature, and gravity are reference-level values because there is no solid surface to stand on.

Audit note

How to read discrepancies

Compact summary boxes, environment notes, and detailed fact tables are now aligned to the same field guide data blocks. This consistency pass was updated on May 5, 2026. Small differences can still appear when a quantity is rounded for readability, when a rocky-planet surface value is contrasted with a giant-planet reference level, or when moon counts change after new confirmations.

Mathematical model

Planet rotation and scale model

Planet meshes are procedural study models: radius, axial tilt, and rotation come from catalog fields, while surface textures are visual aids. The mathematical model does not infer planet shape from a picture.

Rotation phase

\[\theta(t)=\theta_0+\frac{2\pi t}{P_{\mathrm{rot}}}\]

The displayed spin angle advances from the body's rotation period P_rot. Retrograde rotation is represented by the sign of P_rot.

Axial tilt

\[\mathbf{r}_{\mathrm{tilted}}=R_z(\varepsilon)\,\mathbf{r}_{\mathrm{body}}\]

The spin axis is tilted by an explicit obliquity epsilon. The proof is a rigid-body rotation matrix, not an artist-drawn axis.

Scale contract

\[R_{\mathrm{scene}}=k\,R_{\mathrm{catalog}}\]

Scene radius is a scalar multiple of catalog radius unless the user chooses a readability mode. The page states when visual radius is bounded so the model is not mistaken for exact visual scale.

Verification standard: the rendered object must be reproducible from stated equations, catalog parameters, or explicit geometric transforms. Visual reference images may inform presentation only; they are not the source of orbital positions, field vectors, accretion-disk gradients, timing, or engineering layout.

Limitations: browser scenes may use bounded scale, compressed distances, simplified two-body dynamics, schematic transfer curves, or educational approximations where full numerical ephemerides, CFD, finite-element models, or general-relativistic ray tracing are outside the page scope. Those simplifications are part of the model contract, not hidden image-based construction.

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