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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 |
|
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|
| 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
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Solar Energy
It's difficult to comprehend the Sun's energy
output because it's so enormous—386
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.
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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.
Find more Facts
about the Sun on the NASA National Space Science Data
Center Web site.
Learn more about The
Sun on the Nine Planets Web site.
See
current solar images at the Solar
Max 2000 Web site.
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Related
to chapter 2 in the print guide. |
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