Body diameters to scale. Positions and surface artwork are illustrative; Saturn’s rings are excluded.
A change of perspective
8.3675× the diameter. See how the two worlds measure up.
Diameter is a distance across an object. Volume grows with the cube of that distance.
Choose a size to bring this comparison down to Earth.
Oberon: Diameter of a sphere with Oberon's volume. Calculated as twice JPL's mean radius of 761.4 km: 1,522.8 km. The listed radius sigma of 2.6 km becomes a diameter sigma of 5.2 km. This is a volume-equivalent mean, not an equatorial, polar or maximum terrain-to-terrain diameter.
Earth: Twice the source mean radius; body diameter only, excluding rings.
Diameter of a sphere with Oberon's volume. Calculated as twice JPL's mean radius of 761.4 km: 1,522.8 km. The listed radius sigma of 2.6 km becomes a diameter sigma of 5.2 km. This is a volume-equivalent mean, not an equatorial, polar or maximum terrain-to-terrain diameter.
Oberon, a moon of Uranus, has a mean diameter of approximately 1,523 km. The adopted value is 1,522.8 km, calculated from the radius in JPL's satellite physical parameters. Its stated diameter uncertainty is ±5.2 km, so the decimal place does not imply exact knowledge.
Using JPL's mean radii for both bodies gives diameters of 1,522.8 km for Oberon and 3,474.8 km for Earth's Moon. Dividing these gives about 0.438: Oberon is roughly 44% as wide. If the Moon were a circle 10 cm across, Oberon would be about 4.4 cm across. These are calculated diameter comparisons; they do not describe mass, orbital distance or apparent size in the sky. Source: JPL.
Use the same measurement definition for both objects when comparing sizes. A single spherical diameter cannot show local relief or different dimensions along an irregular body's axes. The artwork is illustrative, not a surface map. Read the size comparison methodology for more context.