Pluto Fact Sheet


[Hubble image of Pluto and Charon]

Pluto/Earth Comparison


Bulk parameters

                                  Pluto          Earth      Ratio (Pluto/Earth)
Mass (1024 kg)                    0.01303        5.9726         0.0022
Volume (1010 km3)                 0.697        108.321          0.0064
Equatorial radius (km)	           1185           6378.1        0.186
Polar radius (km)                  1185           6356.8        0.186
Volumetric mean radius (km)        1185           6371.0        0.186         
Ellipticity (Flattening)          0.0000         0.00335        0.0
Mean density (kg/m3)               1869           5514          0.339
Surface gravity (m/s2)            0.62           9.80           0.063
Surface acceleration (m/s2)       0.62           9.78           0.063
Escape velocity (km/s)            1.21          11.19           0.108
GM (x 106 km3/s2)                 0.00087        0.3986         0.0022  
Bond albedo                    0.4 - 0.6         0.306        1.3 - 2.0
Visual geometric albedo        0.5 - 0.7         0.367        1.4 - 1.9
Visual magnitude V(1,0)          -1.0           -3.86             -
Solar irradiance (W/m2)           0.89           1367.6         0.0007
Black-body temperature (K)       37.5          254.3            0.147
Number of natural satellites      5              1
Planetary ring system            No             No


Orbital parameters

                                  Pluto           Earth      Ratio (Pluto/Earth)
Semimajor axis (106 km)         5906.38          149.60          39.482
Sidereal orbit period (days)     90,560          365.256        247.94
Tropical orbit period (days)    Unknown          365.242           -
Perihelion (106 km)             4436.82          147.09          30.164       
Aphelion (106 km)               7375.93          152.10          48.494
Synodic period (days)            366.73             -              -
Mean orbital velocity (km/s)       4.67           29.78           0.157 
Max. orbital velocity (km/s)       6.10           30.29           0.201     
Min. orbital velocity (km/s)       3.71           29.29           0.127    
Orbit inclination (deg)           17.16            0.000           -
Orbit eccentricity                 0.2488          0.0167        14.899
Sidereal rotation period (hrs)  -153.2928         23.9345         6.405
Length of day (hrs)              153.2820         24.0000         6.387
Obliquity to orbit (deg)         122.53           23.44          (2.452)

Pluto Observational Parameters

Discoverer:      Clyde Tombaugh
Discovery Date:  18 February 1930

Distance from Earth
        Minimum (106 km)         4284.7
        Maximum (106 km)         7528.0
Apparent diameter from Earth
        Maximum (seconds of arc)    0.11
        Minimum (seconds of arc)    0.06
Mean values at opposition from Earth
        Distance from Earth (106 km)       5750.54    
        Apparent diameter (seconds of arc)    0.08
        Apparent visual magnitude            15.1      
Maximum apparent visual magnitude            13.65

Pluto Mean Orbital Elements (J2000)

Semimajor axis (AU)                 39.48168677  
Orbital eccentricity                 0.24880766  
Orbital inclination (deg)           17.14175  
Longitude of ascending node (deg)  110.30347  
Longitude of perihelion (deg)      224.06676  
Mean longitude (deg)               238.92881

Positive Pole of Rotation

Right Ascension: 132.99
Declination    :   -6.16
Reference Date : 12:00 UT 1 Jan 2000 (JD 2451545.0)

Pluto Atmosphere

Surface Pressure: ~3 microbar
Average temperature: ~50 K (-223 C)
Scale height: ~60 km
Mean molecular weight: ~16-25 
Atmospheric composition:  Methane (CH4), Nitrogen (N2)


Charon (P1)

Mean distance from Pluto (km)     19,600        
Sidereal orbit period (days)        6.3872        
Sidereal rotation period (days)     6.3872        
Orbital inclination to Pluto (deg)  0.0       
Orbital eccentricity                0.0
Equatorial radius (km)              604          
Mass (1021 kg)                      1.59        
Mean density (kg/m3)               1720
Surface gravity (m/s2)              0.29
Escape velocity (km/s)              0.59  
Geometric albedo                    0.38
Apparent visual magnitude          16.8

Other Moons of Pluto

                Semi-Major    Orbital     Mean Diameter
                Axis (km)  Period (days)      (km)
Nix (P2)          48,700       24.9         42 x 36
Hydra (P3)        64,750       38.2         55 x 40
Kerberos (P4)     57,750       32.2         13 - 34
Styx (P5)         42,400       20.2         10 - 25

Orbital values are barycentric

bullet Notes on the factsheets - definitions of parameters, units, notes on sub- and superscripts, etc.

bullet Planetary Fact Table - metric units
bullet Planetary Fact Table - U.S. units
bullet Planetary Fact Table - Earth ratio


bullet Pluto Home Page
bullet Directory to other Planetary Fact Sheets

[NASA Logo]
Author/Curator:
Dr. David R. Williams, dave.williams@nasa.gov
NSSDCA, Mail Code 690.1
NASA Goddard Space Flight Center
Greenbelt, MD 20771
+1-301-286-1258


NASA Official: Ed Grayzeck, edwin.j.grayzeck@nasa.gov
Last Updated: 13 August 2015, DRW