Saturn · natural satellite

Janus

Mean diameter: 178.4 km
Mean orbital distance: 151,500 km from centre
Orbital period: 0.697 Earth days

Compared with our Moon

Janus · 178.4 km

Moon · 3,474.8 km

One diameter scale. Circle shapes compare volume-equivalent diameters; irregular moons are not spheres.

Orbit & discovery

Surface gravity: 0.016 m/s²
Discovery: 1966, 1980
Discoverer / team: A. Dollfus (1966), D. Pascu (1980)
Provisional designation: S/1980 S1
JPL satellite ID: 610
Orbital eccentricity: 0.007
Inclination: 0.2 degrees

Inclination reference: Laplace. Mean-element epoch: 2000-01-01.5 TDB · SAT415.

Diameters use volume-equivalent mean radii, including for irregular bodies. Mean orbital elements describe an orbit; they are not live positions. Missing physical measurements remain unavailable.

Physical measurements & uncertainties

Mean radius · km: 89.2 ±0.8 [1]
GM · km³/s²: 0.12662 ±0.00007 [SAT415]
Density · g/cm³: 0.6381 ±0.0172 [*]

Missions in the Saturn system · 5 records

5 launches · 0 linked events

These records cover the planetary system. A system mission did not necessarily visit this moon. Dedicated targets are marked separately; programme events include the journey and briefings. Launch outcomes do not establish arrival, landing success or present spacecraft operation.

Dedicated targets only

PLANETARY SYSTEM · UPCOMING