Callisto
Callisto is a natural satellite of Jupiter, with a heavily cratered icy surface.
How big is it?
4,821 km · mean diameter
Mean diameter · approximate
A little perspective
Callisto vs Mercury: diameter comparison
The mean diameter of Mercury is about 1.01 times the mean diameter of Callisto.
Callisto is a natural satellite of Jupiter, with a heavily cratered icy surface.
Mercury is a rocky planet orbiting closest to the Sun in the Solar System.
Both rulers start at the same zero and share one linear scale. Artwork keeps its original proportions.
Measurements, assumptions & sources +
Callisto
Mean diameter: 4,821 km; approximate.
Rounded mean-radius model of Callisto. The derived area and volume describe a sphere; surface terrain and flattening are omitted.
NASA JPL — Planetary satellite physical parameters
The marked mean diameter is calibrated. Unmeasured illustration details are representative.
Mercury
Mean diameter: 4,879 km; approximate.
Mean-radius spherical model for Mercury; actual shape is not perfectly spherical.
NASA JPL — planetary physical parameters
The marked mean diameter is calibrated. Unmeasured illustration details are representative.
Use the visual comparison to explore its scale, then check the measurements and sources.
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Why this measurement?
Why we use 4,821 km
We compare the mean diameter of Callisto. This is an estimate; check the notes for its rounding and uncertainty.
Rounded mean-radius model of Callisto. The derived area and volume describe a sphere; surface terrain and flattening are omitted.
The marked horizontal span follows the measured feature, not the edges of the image. How calibrated comparisons work →
Recorded properties
Dimensions and measurements
| Property | Selected value | Recorded range | Basis |
|---|---|---|---|
| 4,821 km | Not recorded | approximate | |
| 73,000,000 km² | Not recorded | derived | |
| 5.865 × 10¹⁰ km³ | Not recorded | derived | |
| 1.076 × 10²⁰ t | Not recorded | derived | |
| 1.236 m/s² | Not recorded | derived |
Around this scale
Explore nearby values.
Compare examples with lower, similar and higher values. Each card names the measurement being compared.
Nearest lower valuePlanets, moons and spaceMoon3,475 kmMean diameterThe Moon is Earth’s natural satellite and the brightest large object in Earth’s night sky.
Around the same scalePlanets, moons and spaceTitan5,150 kmMean diameterTitan is a natural satellite of Saturn, with a thick nitrogen-rich atmosphere and surface lakes of hydrocarbons.
Nearest higher valuePlanets, moons and spaceMercury4,879 kmMean diameterMercury is a rocky planet orbiting closest to the Sun in the Solar System.Sources and method
Want to check the number?
The source records and measurement method remain available for inspection.
- NASA JPL — Planetary satellite physical parametersPublished mean radii and gravitational parameters GM. Spherical areas, volumes, masses and local gravity are explicitly derived.
More ways to see it
Curated comparisons
There’s always another scale
Follow your curiosity.
SpaceMoon3,475 kmThe Moon is Earth’s natural satellite and the brightest large object in Earth’s night sky.
SpaceEarth12,740 kmEarth is the rocky planet on which we live and the third planet from the Sun.
SpacePluto2,377 kmPluto is a dwarf planet in the Kuiper Belt, composed of rock and ice and orbiting the Sun.
SpaceJupiter139,800 kmJupiter is a giant planet composed mainly of hydrogen and helium, orbiting the Sun beyond the asteroid belt.SpaceMercury4,879 kmMercury is a rocky planet orbiting closest to the Sun in the Solar System.SpaceTitan5,150 kmTitan is a natural satellite of Saturn, with a thick nitrogen-rich atmosphere and surface lakes of hydrocarbons.
SpaceGanymede5,262 kmGanymede is a natural satellite of Jupiter and contains a magnetic field generated by its partially liquid core.
SpaceIo3,643 kmIo is a natural satellite of Jupiter, covered with active volcanoes and sulphur deposits.