Comets in our solar system.

Entity["Comet",name] or

represents an entity of type "Comet".


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


  • Ageage
    AlphanumericNamealphanumeric name
    AlternateNamesalternate names
    AngularDiameterFromEarthangular diameter
    AngularRadiusFromEarthangular radius
    Aphelionlargest distance from the Sun
    Apoapsislargest distance from Sun
    ApoapsisTimenext apoapsis time
    ApoapsisTimeLastlast apoapsis time
    ApparentAltitudeapparent altitude
    ApparentMagnitudeapparent magnitude
    AscendingNodeLongitudelongitude of ascending node Ω
    AverageDistanceFromEarthaverage distance from Earth
    AverageOrbitalCentripetalForceaverage orbital centripetal force
    AverageOrbitDistanceaverage orbit distance
    AverageOrbitVelocityaverage orbit velocity
    AverageVelocityAroundSunaverage heliocentric velocity
    BooleanRiseabove the horizon
    DailyTimeAboveHorizondaily time above horizon
    DestructionDatedestruction date
    Diameteraverage diameter
    DiscoveryDatediscovery date
    DistanceFromEarthdistance from Earth
    DistanceFromSundistance from Sun
    EarthMOIDEarth minimum orbit intersection distance
    EccentricAnomalyeccentric anomaly
    Eccentricityorbital eccentricity
    EntityClassesentity classes
    EntityTypeListentity type list
    EquatorialDiameterequatorial diameter
    EquatorialRadiusequatorial radius
    FarthestPlanetfarthest planet
    GalacticLatitudegalactic latitude
    GalacticLongitudegalactic longitude
    GeocentricEclipticLatitudegeocentric ecliptic latitude
    GeocentricEclipticLongitudegeocentric ecliptic longitude
    GravitationalConstantMassProductgravitational constant mass product
    GreenwichHourAngleGreenwich hour angle
    HeliocentricEclipticLatitudeheliocentric ecliptic latitude
    HeliocentricEclipticLongitudeheliocentric ecliptic longitude
    HelioCoordinatesheliocentric XYZ coordinates
    HelioVelocityVectorheliocentric velocity vector
    IAUNameIAU name
    Inclinationorbital inclination
    LocalHourAnglelocal hour angle
    MajorAxisorbital major axis
    MaximalAltitudeTimenext maximum altitude time
    MaximumOrbitalCentripetalForcemaximum orbital centripetal force
    MeanAnomalymean anomaly
    MeanMotionmean motion
    MinimumOrbitalCentripetalForceminimum orbital centripetal force
    MinorAxisorbital minor axis
    NearestPlanetnearest planet
    NuclearMagnitudeParameternuclear magnitude parameter
    NuclearMagnitudeSlopeParameternuclear magnitude slope parameter
    ObjectTypeobject type
    OppositionTimeLastlast opposition time
    OppositionTimeNearestnearest opposition time
    OppositionTimeNextnext opposition time
    OrbitalCentripetalForceorbital centripetal force
    OrbitCenterorbit center
    OrbitCircumferenceorbit circumference
    OrbitPathorbit path
    OrbitPeriodorbital period
    OrbitRulesorbit rules
    Periapsissmallest distance from Sun
    PeriapsisArgumentargument of periapsis ω
    PeriapsisLongitudelongitude of periapsis ϖ
    PeriapsisTimenext periapsis time
    PeriapsisTimeLastlast periapsis time
    Perihelionnearest distance from the Sun
    PrimaryDesignationprimary designation
    Radiusaverage radius
    RetrogradeApparentMotionQueryapparent direction
    RightAscensionright ascension
    RiseTimenext rise
    RotationPeriodrotation period
    SemimajorAxisorbital semimajor axis
    SemiminorAxisorbital semiminor axis
    SetTimenext set
    SiderealHourAnglesidereal hour angle
    SolarConjunctionTimeLastlast solar conjunction time
    SolarConjunctionTimeNearestnearest solar conjunction time
    SolarConjunctionTimeNextnext solar conjunction time
    SolarDaysolar day
    SphereOfInfluenceRadiussphere of influence radius
    SurfaceAreasurface area
    TotalMagnitudeParametertotal magnitude parameter
    TotalMagnitudeSlopeParametertotal magnitude slope parameter
    TrueAnomalytrue anomaly
    VelocityAroundSuninstantaneous heliocentric velocity
    ZenithAnglezenith angle


  • "Comet" entities include a subset of modern and historical comets that have been observed.
  • "Comet" entity classes include groups based on orbit type, but also groups based on definitions such as "great comets".
  • Due to the fact that most comets have never been visited directly by spacecraft, most available data is focused on orbital parameters. Physical properties such as mass and radius are more sparse.
  • Some properties are available for the "Comet" entity type as a whole and can be given using the form EntityValue["Comet",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["Comet",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  (7)

Use for discovery:

Find the current distance to a comet:

Find the next periapsis time of a comet:

Get a list of available classes of comets:

Rank comets in a class by orbit period:

Retrieve a dataset of all available properties for an entity:

Find comets with the 3 least eccentric orbits:

Scope  (4)

Implicit Entity Classes  (1)

Represent all of the comets with fewer than 15 moons:

Get a list of all the comets:

Property Classes  (1)

Represent equatorial coordinate properties associated with comets:

Get a list of available property classes for comets:

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:

Neat Examples  (1)

Plot the orbits of classes of comets: