| • Science | • People | • Locations | • Timeline |
| Discovery | |
|---|---|
| Discovered by | Laques and Lecacheux |
| Discovered in | 1980 |
| Orbital characteristics | |
| Semimajor axis | 377,400 km |
| Eccentricity | 0.0022 |
| Orbital period | 65h 41m 05s |
| Inclination | 0.02° |
| Satellite of | Saturn |
| Physical characteristics | |
| Mean diameter | 32 km (36 × 32 × 30) |
| Mass | ? kg |
| Mean density | ? g/cm3 |
| Surface gravity | ? m/s2In physics, acceleration (symbol: a is defined as the rate of change (or time derivative) of velocity. It is thus a vector quantity with dimension length/ time². In SI units, this is metre/second². To accelerate an object is to change its velocity over a |
| Escape velocityFor the video game title, see Escape Velocity (computer game). In physics, for a given gravitational field and a given position, the escape velocity is the minimum speed an object without propulsion, at that position, needs to have to move away indefinite | ?km/s |
| Rotation periodprograde planet like the Earth, the sidereal day is shorter than the solar day. At time 1, the sun and a certain distant star are both overhead. At time 2, the planet has rotated 360° and the distant star is overhead again (1→2 one sidereal day). | ? |
| Axial tiltAxial tilt is an astronomical term regarding the inclination angle of a planet's rotation axis in relation to its orbital plane. It is also called obliquity . A planet whose rotation axis were perpendicular to the orbital plane would have an axial tilt of | ?° |
| AlbedoNote: This article discusses the physical or planetological property of albedo. For other usage, see Albedo (disambiguation). The albedo is a measure of reflectivity of a surface or body. It is the ratio of electromagnetic radiation reflected to the amoun | ? |
| Surface temperatureTemperature is the physical property of a system which underlies the common notions of "hot" and "cold"; the material with the higher temperature is said to be hotter. General description The formal properties of temperature are studied in thermodynamics. | ? KThe kelvin (symbol: K is the SI unit of temperature, and is one of the seven SI base units. It is defined by two facts: zero kelvin is absolute zero (when molecular motion stops), and one kelvin is the fraction 1/273. 16 of the thermodynamic temperature o |
| Atmosphere | none |
Helene ("HELL uh nee" or "hel LEE nee") is a moon of Saturn. It was discovered by Pierre Laques and Jean Lecacheux in 1980 from ground-based observations at Pic du Midi Observatory, and was designated 1980 S 6. In 1988 it was officially named after Helene of Greek mythology.
It is co-orbital with Dione and located in its leading Lagrangian point (L4) and hence, before it received its permanent name of "Helene" it was usually referred to as "Dione B".
| Saturn |
|---|
| Janus' group | Mimas | Enceladus | Tethys | Dione | Rhea |
| Titan | Hyperion | Iapetus | Siarnaq's group | Phoebe's group |
| (For other moons, see: Saturn's natural satellites) |
| see also: Cassini-Huygens |