OVERVIEW
] MOONIo is a moon of Jupiter. It orbits Jupiter at a mean distance of 421 800 . It has a mass of 0.01 and a mean radius of 0.29 · 1821 . It was discovered in 1610.
The most volcanically active body in the Solar System, kneaded by Jupiter's tides until its surface constantly resurfaces itself in sulphur.
- WHAT IT IS
- Moon of Jupiter
- HOW FAR
- 421 800
- HOW BIG
- 0.29 · 1821
- ONE ORBIT TAKES
- 42.3
Its average distance from Jupiter, not from Earth.
Its mean radius: half the width across.
One trip round Jupiter.
IMAGES
] 2 FRAMES- NASA / JPL / University of Arizona
Public domain - NASA / SWRI / MSSS / Jason Perry
CC BY-SA 3.0
CATALOG DATA
] 8 FIELDSThe raw catalogue values, as the source published them, with the error bars where one was published — sorted by what each set of figures is about rather than by the order they happened to be stored in.
WHAT IT IS MADE OF
What the object is in itself, rather than how it happens to look from here.
- Mean density
- 3.5276 ±0.0029
THE ORBIT
The shape of the path, where the object sits on it, and the instant those figures were true of. An orbit is a fit to observations and drifts away from the real one either side of its epoch.
- Orbits
- Jupiter
- Orbital period
- 1.762732
- Eccentricity
- Inclination
- 0
WHEN IT WAS FOUND
Who first saw it, from where, and by what method.
- Discovered by
- Galileo
OTHER NAMES AND NUMBERS
The identifiers other catalogues file this object under, for anyone joining this data to theirs.
- JPL satellite code
- 501
WHERE THESE FIGURES CAME FROM
Which catalogue, paper or model each of the fields above was read from, where the source named one.
- Ephemeris
- JUP365
ALSO KNOWN AS
] 1 DESIGNATIONS- Common name Io
CITE THIS PAGE
] DR1This page is live and its numbers move when an upstream refreshes, so the citation names the release the rows belong to rather than the day you read them. The release itself is frozen, republished as a bundle, and is what a data-availability statement should point at.
SpaceCatalog. Io [catalogue entry]. Data release DR1 (2026-08-21). https://spacecatalog.org/object/io
@misc{spacecatalog_io,
author = {{SpaceCatalog}},
title = {{Io}},
howpublished = {SpaceCatalog, data release DR1 (2026-08-21)},
year = {2026},
url = {https://spacecatalog.org/object/io},
note = {Catalogue entry, data release DR1 (2026-08-21). Values from JPL Planetary Satellite Data.}
}The values above were taken from JPL Planetary Satellite Data — Public domain (NASA/JPL). Citing this page does not replace citing that catalogue.