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The Sun seen in the light emitted by hydrogen atoms, showing violent activity on and above the Sun's surface. Source: The Sun, by the University of Arizona. |
SOME IMAGES OF THE SUN
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The Sun seen in the light emitted by hydrogen atoms, showing violent activity on and above the Sun's surface. Source: The Sun, by the University of Arizona. |
There are three super web sites where you can find excellent introductions to the Sun. You should read them all (at least the text parts, which are fairly brief). They have many links that will take you deep into the science of the Sun and many fascinating images and movies. But watch out for the movies! They may take several minutes, in some cases more than a half-hour, to download over a modem.
Start with The Sun, by the University of Arizona. Then have a look at Views of the Sun, which has a spectacular gallery of images and movies of the Sun.
1. BASIC PROPERTIES
Distance from Sun to Earth: 1 AU = 1.5 x 108 km = 8.3 light-minutes
(Denver -> NY = 0.01 light-seconds; Earth -> Moon = 1.3 light-sec)
Diameter: DSun
= 1.4 x 106 km = 5 lt-sec = 109 x Earth's Diameter
Mass: MSun = 2 x 1030 kg = (1/3) x 106 Mass of Earth
Density: Average = 1.4 g cm-3 (slightly more than water); Central = 150 g cm-3; Photosphere = 3.5 x 10-7 g cm-3 = 1/3000 x air.
Temperature: Central: 1.5 x 107 K; Photosphere: 6000 K; Sunspots: 4800 K; Corona: 106 - 107 K.
Composition (by mass): 72% Hydrogen, 26% Helium, 2% all other elements. Gaseous
Rotation period: 25 days (equator); 28 days (higher latitudes); 31 days (polar).
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The temperature above the Sun's photosphere rises rapidly to more than a million degrees in the Corona |
