Space · Mean-diameter reference · idealized sphere
Mercury diameter and size comparison
Mercury’s mean diameter is 4,878.8 kilometers in the JPL reference. It is larger across than the Moon but smaller across than Ganymede.
4878800 m
Sourced measurement- Measurement
- Mean diameter · twice JPL mean radius
- Subject or version
- Mean-diameter reference · idealized sphere
- In kilometers
- 4,878.8 km (1 km = 1,000 m)
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A little more perspective
The comparison uses twice the 2,439.4-kilometer mean radius, not twice the separately listed 2,440.53-kilometer equatorial radius. A common diameter convention makes that distinction explicit.
The displayed diameter is 2 × 2,439.4 km = 4,878.8 km. Doubling the source radius uncertainty gives ±0.2 km for diameter. The source defines mean radius through an equivalent-volume sphere. Its review date is not a new measurement date.
Quick facts
Mercury’s mean diameter is 4,878.8 kilometers in the JPL reference. It is larger across than the Moon but smaller across than Ganymede.
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Sources and measurement notes
Source review recorded . Maintained by Ishan Karunaratne. Suggest a correction with a source and the exact measurement being compared.