Io (Moon of Jupiter)
3,643 km (2,264 mi)
Diameter (twice the radius)
The most volcanic world in the Solar System. Diameter: 3,643 km, a little bigger than our Moon.
Published
How big is that?
3,643 km is 412 times Mount Everest and 29% of Earth.
Io is the 15th largest of the 39 Cosmic Scale objects, and the 15th largest of the 109 objects across all three SizeItUp games.
Size comparison
To scale, smallest to largest: Io in orange beside the Cosmic Scale objects nearest in size, in teal.
| Object | Size | vs Io |
|---|---|---|
| Europa (Moon of Jupiter)An icy moon with an ocean hidden under its cracked crust. | 3,121.6 km across | 86% of the size |
| The MoonEarth's only natural satellite. | 3,475 km across | about the same |
| Io (Moon of Jupiter) | 3,643 km across | – |
| Valles Marineris (Mars)The great canyon system of Mars, seen from above and measured end to end. | 3,870 km long | 1.1× bigger |
| Callisto (Moon of Jupiter)Jupiter's battered outer giant moon, covered in craters. | 4,820.6 km across | 1.3× bigger |
In other units
| Metres | 3,643,000 |
|---|---|
| Kilometres | 3,643 |
| Feet | 11,950,000 |
| Miles | 2,264 |
How it's measured
Diameter (twice the radius). NASA Jovian Satellite Fact Sheet: radius 1,821.5 km.
Fact sheets list a radius; the diameter here is twice that.
Sources
- nssdc.gsfc.nasa.gov: Io (I): radius 1821.5 km.
Checked against the source on .
Could you have guessed it by eye?
Io is one of the objects in Cosmic Scale, a daily size comparison game: you stretch a shape to the size you think is right beside one you know.