Fact Sheet: The Sun (Comparison with Earth)


Bulk parameters

      
Sun Earth Ratio (Sun/Earth)
Mass (1024 kg) 1,988,500. 5.9726 333,000.
GM (x 106 km3/s2) 132,712. 0.3986 333,000.
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. 5514. 0.255
Surface gravity (eq.) (m/s2) 274.0 9.78 28.0
Escape velocity (km/s) 617.6 11.19 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

North Pole of Rotation

Right Ascension: 286.13
Declination    :  63.87
Reference Date : 1.5 Jan 2000 (JD 2451545.0)

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 
Pressure at bottom of photosphere (optical depth = 1): 125 mb
Effective temperature: 5778 K
Temperature at top of photosphere:  4400 K
Temperature at bottom of photosphere:  6600 K
Temperature at top of chromosphere:  ~30,000 K
Photosphere thickness:  ~500 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


Note: Fact Sheet is taken from NASA website: http://nssdc.gsfc.nasa.gov/planetary/factsheet/sunfact.html

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