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Sun Fact Sheet

[Global view of the Sun]

Sun/Earth Comparison

Bulk parameters

                                     Sun          Earth      Ratio (Sun/Earth)
Mass (1024 kg)                     1,989,100.      5.9736      332,950.    
GM (x 106 km3/s2)                    132,712.      0.3986      332,950.  
Volume (1012 km3)                  1,412,000.      1.083     1,304,000. 
Volumetric mean radius (km)         696,000.       6371.      109.2
Mean density (kg/m3)                1408.          5520.        0.255       
Surface gravity (eq.) (m/s2)         274.0         9.78        28.0     
Escape velocity (km/s)               617.7        11.2         55.2     
Ellipticity                         0.00005        0.0034       0.015
Moment of inertia (I/MR2)              0.059       0.3308       0.178      
Visual magnitude V(1,0)              -26.74       -3.86          -  
Absolute magnitude                    +4.83
Luminosity (1024 J/s)                384.6
Mass conversion rate (106 kg/s)     4300.         
Mean energy production (10-3 J/kg)     0.1937
Surface emission (106 J/m2s)          63.29
Spectral type                         G2 V

Model values at center of Sun:
Central pressure:     2.477 x 1011 bar                 
Central temperature:  1.571 x 107 K
Central density:      1.622 x 105 kg/m3

Rotational and Orbital parameters

                                          Sun        Earth      Ratio (Sun/Earth)
Sidereal rotation period (hrs)*         609.12       23.9345     25.449     
Obliquity to ecliptic (deg.)              7.25       23.45        0.309
Speed relative to nearby stars (km/s)    19.4
*This is the adopted period at 16 deg. latitude - the actual rotation rate varies with latitude L as:
( 14.37 - 2.33 sin2 L - 1.56 sin4 L ) deg/day

Sun Observational Parameters

Apparent diameter from Earth
        At 1 A.U.(seconds of arc)  1919.
        Maximum (seconds of arc)   1952.
        Minimum (seconds of arc)   1887.
Distance from Earth
        Mean (106 km)              149.6
        Minimum (106 km)           147.1
        Maximum (106 km)           152.1

Solar Magnetic Field

Typical magnetic field strengths for various parts of the Sun 

Polar Field:  1 - 2 Gauss 
Sunspots:  3000 Gauss
Prominences:  10 - 100 Gauss
Chromospheric plages:  200 Gauss
Bright chromospheric network:  25 Gauss
Ephemeral (unipolar) active regions:  20 Gauss

Solar Atmosphere

Surface Gas Pressure (top of photosphere): 0.868 mb  
Effective temperature: 5778 K
Temperature at bottom of photosphere:  6600 K
Temperature at top of photosphere:  4400 K
Temperature at top of chromosphere:  ~30,000 K
Photosphere thickness:  ~400 km
Chromosphere thickness:  ~2500 km
Sun Spot Cycle:  11.4 yr.

Photosphere Composition: 
    Major elements: H - 90.965%, He - 8.889%
    Minor elements (ppm): O - 774, C - 330, Ne - 112, N - 102
			  Fe - 43, Mg - 35, Si - 32, S - 15
If no sub- or superscripts appear on this page - for example, if the "Mass" is given in units of "(1024 kg)" - you may want to check the notes on the sub- and superscripts.

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

* Directory to other Planetary Fact Sheets
* NSSDC Planetary Home Page
Questions and comments about this page should be addressed to:
Dr. David R. Williams, dwilliam@nssdc.gsfc.nasa.gov, (301) 286-1258
NSSDC, Mail Code 633, NASA/Goddard Space Flight Center, Greenbelt, MD 20771
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NASA Official: J. H. King, king@nssdca.gsfc.nasa.gov
Last Updated: 16 January 1998, DRW