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Sun Facts

The Sun is rather ordinary when it comes to stars. In fact, there are 100 billion stars in our galaxy that are similar to the Sun. What makes our star unique is that it is ours—responsible for light, heat, and life as we know it.

In our solar system the Sun is by far the largest object. More than 99.8% of the total mass of our solar system is contained within the Sun. Below are some other facts about the Sun, compared with Earth where appropriate.

Bulk parameters
  Sun Earth Ratio (Sun/Earth)
Mass (1024 kg) 1,989,100 5.9736 332,950
Gravitational Pull
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 5515 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
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 4300    
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 Kelvin
Central density: 1.622 x 105 kg/m3

Credit: Adapted from NASA's National Space Science Data Center Sun Fact Sheet

Solar Energy

It's difficult to comprehend the Sun's energy output because it's so enormous386 billion megawatts, produced by ongoing nuclear reactions. To put this into perspective, just one of those megawatts is enough to power 1,000 American homes, an entire small town.

The Sun
This solar image was taken by the Extreme Ultraviolet Imaging Telescope aboard the Solar and Heliospheric Observatory (SOHO) spacecraft.

The energy that the Sun emits is created deep within its core. Here intense pressure (340 billion times Earth's air pressure at sea level) and heat (15 million degrees Celsius; 27 million degrees Fahrenheit) cause nuclear reactions to take place.

globe icon Find more Facts about the Sun on the NASA National Space Science Data Center Web site. (Requires an Internet connection)

globe icon Learn more about The Sun on the Nine Planets Web site. (Requires an Internet connection)

globe icon See current solar images at the Solar Max 2000 Web site.
(Requires an Internet connection)

Related to chapter 2 in the print guide.
Related Materials

See some different views of the Sun in Filtered Images.

Get an overview of the Sun and its relationship with the Earth in the Sun-Earth Connection.

Glossary Terms

Click for the definitions of the following words that are used on this page:(Definitions appear in a pop-up window.)

ultraviolet radiation

View the full, printable version of the glossary.

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