Body diameters to scale. Positions and surface artwork are illustrative; Saturn’s rings are excluded.
A change of perspective
4.7102× 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.
Triton: Diameter calculated as twice JPL's volume-equivalent mean radius: 2 × 1352.60 km = 2705.2 km. The listed radius sigma of 2.40 km becomes a diameter sigma of 4.8 km. This describes an equal-volume sphere, rather than an equatorial, polar or longest-axis measurement.
Earth: Twice the source mean radius; body diameter only, excluding rings.
Diameter calculated as twice JPL's volume-equivalent mean radius: 2 × 1352.60 km = 2705.2 km. The listed radius sigma of 2.40 km becomes a diameter sigma of 4.8 km. This describes an equal-volume sphere, rather than an equatorial, polar or longest-axis measurement.
Doubling those radii gives 2,705.2 km for Triton and 3,474.8 km for Earth's Moon. Their diameter ratio is about 0.779. If the Moon were drawn 10 cm wide, Triton would be about 7.8 cm wide. This compares physical widths; it does not describe their apparent sizes in the sky.
JPL defines mean radius using a sphere of equal volume and attributes these radii to Archinal and colleagues' 2018 report. Doubling Triton's listed radius and sigma gives 2,705.2 ± 4.8 km. The decimal is retained for calculation, not to imply exactness. Source: JPL.
Equatorial and polar diameters describe particular directions. An irregular body's longest dimension is also a different measure. Use matching measurement definitions when comparing objects; see our size comparison methodology.
The artwork is illustrative. Its colors and surface details are not measurement evidence.