Natural satellites in the solar system.

Entity["PlanetaryMoon",name] or

represents an entity of type "PlanetaryMoon".


gives the value of a specified property.


gives the value of a list of properties.


gives the value of a specified property modified by qualifier rules quali->vali.


gives the value of a property associated with a particular date specification.


represents a class of entities with values of propi defined by speci.

Sample Entities

Sample Entity Classes


  • AbsoluteMagnitudeHabsolute magnitude H
    AlphanumericNamealphanumeric name
    AlternateNamesalternate names
    AltitudeMaximumnext maximum altitude
    AltitudeTransitnext transit altitude
    AngularDiameterFromEarthangular diameter
    AngularRadiusFromEarthangular radius
    Apoapsislargest distance from orbit center
    ApoapsisTimenext apoapsis time
    ApoapsisTimeLastlast apoapsis time
    ApparentAltitudeapparent altitude
    ApparentMagnitudeapparent magnitude
    AscendingNodeLongitudelongitude of ascending node Ω
    AtmosphericCompositionatmospheric composition
    AtmosphericPressureatmospheric pressure
    AverageDistanceFromEarthaverage distance from Earth
    AverageOrbitDistanceaverage orbit distance
    AverageOrbitVelocityaverage orbit velocity
    AverageTemperatureaverage temperature
    AzimuthRiseazimuth at rise
    AzimuthSetazimuth at set
    BooleanRiseabove the horizon
    CylindricalEquidistantTexturecylindrical equidistant texture
    DailyTimeAboveHorizondaily time above horizon
    Densitymean density
    Diameteraverage diameter
    DiscoveryYeardiscovery year
    DistanceFromEarthdistance from Earth
    DistanceFromSundistance from Sun
    EccentricAnomalyeccentric anomaly
    Eccentricityorbital eccentricity
    EffectiveTemperatureeffective temperature
    EntityClassesentity classes
    EquatorialAngularVelocityequatorial angular velocity
    EquatorialCircumferenceequatorial circumference
    EquatorialDiameterequatorial diameter
    EquatorialDiameterAlongOrbitequatorial diameter along orbit
    EquatorialDiameterTowardPlanetequatorial diameter toward planet
    EquatorialFrequencyequatorial frequency
    EquatorialRadiusequatorial radius
    EquatorialRadiusAlongOrbitequatorial radius along orbit
    EquatorialRadiusTowardPlanetequatorial radius toward planet
    EscapeVelocityescape velocity
    FarthestPlanetfarthest planet
    GalacticLatitudegalactic latitude
    GalacticLongitudegalactic longitude
    GravitationalConstantMassProductgravitational constant mass product
    GreenwichHourAngleGreenwich hour angle
    HeliocentricLatitudeheliocentric latitude
    HeliocentricLongitudeheliocentric longitude
    HelioCoordinatesheliocentric XYZ coordinates
    HillRadiusHill radius
    Inclinationorbital inclination
    LocalHourAnglelocal hour angle
    MajorAxisorbital major axis
    MaximalAltitudeTimenext maximum altitude time
    MaximumTemperaturemaximum temperature
    MinimumTemperatureminimum temperature
    MinorAxisorbital minor axis
    MomentOfInertiarotational moment of inertia
    NearestPlanetnearest planet
    ObjectTypeobject type
    OrbitalAngularMomentumorbital angular momentum
    OrbitalKineticEnergyorbital kinetic energy
    OrbitalMomentOfInertiaorbital moment of inertia
    OrbitCenterorbit center
    OrbitCircumferenceorbit circumference
    OrbitPeriodorbital period
    Periapsissmallest distance from orbit center
    PeriapsisArgumentargument of periapsis ω
    PeriapsisTimenext periapsis time
    PeriapsisTimeLastlast periapsis time
    PolarDiameterpolar diameter
    PolarRadiuspolar radius
    Radiusaverage radius
    RetrogradeApparentMotionQueryapparent direction
    RightAscensionright ascension
    RiseTimenext rise
    RocheLimitRoche limit
    RotationalAngularMomentumrotational angular momentum
    RotationPeriodrotation period
    SemimajorAxisorbital semimajor axis
    SemiminorAxisorbital semiminor axis
    SetTimenext set
    SiderealHourAnglesidereal hour angle
    SolarDaysolar day
    SolidAngleFromEarthsolid angle
    StationaryOrbitRadiusstationary orbit radius
    StationaryOrbitSpeedstationary orbit speed
    SunElongationelongation from the Sun
    SurfaceAreasurface area
    TexturedSurface3D graphic
    TransitTimenext transit time
    TrueAnomalytrue anomaly


  • "PlanetaryMoon" entities include the natural satellites of all eight planets recognized by the International Astronomical Union, as well as natural satellites of some minor planets such as Pluto or Eris in the Kuiper Belt.
  • "PlanetaryMoon" entity classes primarily cover sets of satellites orbiting a common central body, and more generally sets of satellites sharing a common defining feature, such as the Galilean moons of Jupiter and retrograde moons.
  • Some properties are available for the "PlanetaryMoon" entity type as a whole and can be given using the form EntityValue["PlanetaryMoon",property]. Such properties include:
  • "Properties"the list of available properties
    "PropertyCanonicalNames"the standard names of available properties
    "SampleEntities"a sample list of available entities (typically of length 10)
    "SampleEntityClasses"a sample list of available entity classes (typically of length 10)
    "EntityCount"number of entities available
    "Entities"the list of available entities
    "EntityCanonicalNames"the standard names of available entities
    "EntityClasses"the list of available entity classes
    "EntityClassCanonicalNames"the standard names of available entity classes
    "PropertyClasses"the list of available property classes
    "PropertyClassCanonicalNames"the standard names of available property classes
    "PropertyCount"number of properties available
  • The following annotations can be used in the third argument of EntityValue["PlanetaryMoon",property,annotation]:
  • "Source"source information for the property
    "Date"the date associated with the entity-property value (if any)
    "EntityAssociation"an association of entities and entity-property values
    "PropertyAssociation"an association of properties and entity-property values
    "EntityPropertyAssociation"an association in which the specified entities are keys, and values are a nested association of properties and entity-property values
    "PropertyEntityAssociation"an association in which the specified properties are keys, and values are a nested association of entities and entity-property values
    "Dataset"a dataset in which the specified entities are keys, and values are an association of property names and entity-property values
  • The following annotations can be used in the second argument of EntityValue[property,annotation]:
  • "Qualifiers"the list of possible qualifiers for the property
    "QualifierValues"the list of possible values that can be given to each qualifier
    "DefaultQualifierValues"the list of default values for the property's qualifiers
    "Description"a brief textual description of the property
    "Definition"a detailed textual definition of the property
    "PhysicalQuantity"the physical quantity associated with the entity-property value
    "Unit"the unit associated with the entity-property value
  • A qualifier value of Automatic indicates that an applicable format of values can be used; e.g. for the "Date" qualifier, this includes a proper date or date span.


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Basic Examples  (4)

Use for entity discovery:

Find a property value for an entity:

Retrieve a dataset of all available properties for an entity:

Find the three most massive moons:

Scope  (9)

Look up the orbit periods of the moons of Neptune:

The known satellites of Neptune:

Diameter of each satellite:

Orbital semimajor axis:

The minor planet Eris has one known satellite:

Orbital semimajor axis:

Location qualifiers can accept an explicit GeoPosition, location-based Entity objects or queries that evaluate to one of these:

Implicit Entity Classes  (1)

Represent all of the moons with radius greater than 700 miles:

Get a list of all the moons:

Property Classes  (1)

Represent equatorial coordinate properties associated with moons:

Get a list of available property classes for moons:

Find the list of properties included in a property class:

Obtain the property values for the properties in a property class for an entity:

Qualifiers  (2)

Some properties accept qualifiers:

The "Location" qualifier, which specifies the location of the observer, can accept an explicit GeoPosition, location-based Entity objects or queries that evaluate to one of these:

Dates  (1)

Date qualifiers can accept an explicit DateObject or queries that evaluate to a DateObject:

Date qualifiers can also be specified using Dated:

Geo Computation  (1)

Create maps of moons:

Applications  (3)

The corresponding plot for all known planetary moons, with a line for each planet:

Find the total number of known planetary moons in the solar system:

Make a log-rank plot of the masses of the moons, with names as tooltips:

Relations to Other Entity Types  (1)

"PlanetaryMoon" entities can be combined with "SolarSystemFeature" entities to create maps with labeled features:

Neat Examples  (1)

Plot diameter against discovery year for the known moons of Saturn: