Key facts
- Scale fact
- 3,643 kmdiameter
- Estimated age
- ~4.5 billion years
- Composition
- Silicate rock with sulfur-rich surface deposits
Io
3,643 kmdiameter
Visual creditGalileo 1999 / NASA / JPL / University of Arizona / Public domainSource: Wikimedia Commons
Details
Io is Jupiter's third-largest moon and the most volcanically active world in the Solar System. Tidal flexing by Jupiter, sustained by orbital resonance with Europa and Ganymede, keeps its interior hot enough to renew the surface with lava flows and sulfur-rich deposits.
Io’s 4:2:1 orbital resonance with Europa and Ganymede prevents its orbit from becoming circular. As its distance from Jupiter changes, solid-body tides flex the moon by as much as about 100 meters and generate enough internal heat to power hundreds of volcanoes. Repeated lava flows and sulfur-rich deposits resurface Io so rapidly that few impact craters remain visible.
Links
- Universe journey
- Asteroid belt & Jupiter
- Wikipedia
- Io on Wikipedia
Size neighbors
Objects near Io on the scale
Sources
References for Io
Measurements and descriptive context are compiled by the Scale of Space team from the references below. If you find an error, please let us know.
- Io — Wikipedia
- Visual reference: Wikimedia Commons (Galileo 1999 / NASA / JPL / University of Arizona, Public domain)
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About
Scale of Space is a scroll-based journey through the universe, placing objects on a single logarithmic scale so you can compare size across an unbroken range.
Guides explain selected parts of that range, while focused views filter the objects by subject.