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Download The Sun: Not An Average Yellow Star
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What is the Sun? The Sun is a Star, but seen close-up. The Sun is giant ball of very hot, mostly ionized hydrogen gas that shines under its own power. What is the Sun? The Sun IS NOT an average, yellow star. Surface Temperature 5800 K The Sun is White The Sun produces all the colors of the rainbow in roughly equal amounts, which is white light. If the Sun were yellow, then white T-shirts would look yellow in the mid-day sunshine. When you observe the Sun safely, by projecting its image through a pinhole camera or a telescope, you see that it is white. Don’t stare directly at the Sun! The UV radiation can damage your eyes. The Sun is Above Average Most stars in the Universe are small, cool, low-mass dwarfs. The Sun is larger, hotter, and more massive than these. There are stars that are much larger, very hot, and many times more massive than the Sun. But these stars are quite rare compared to the Sun or the lowmass stars. The Sun is also not median, mid-range, or most frequent (mode) in the measures of size, temperature, brightness, or mass. Properties of the Sun Property Sun Range for Stars in the Milky Way relative to the Sun Radius 696,000 km (109 times Earth’s radius) 1x10-1 – 2x103 (more stars smaller than larger) Rotation Rate 27 days (equator) to 31 days (poles) Luminosity (Power Output) 3.8 x 1026 watts 4x10-2 – 9x106 (more stars less luminous than more luminous) Surface Temperature 5,800 K (average) 1.5x103 – 3x104 K (more stars cooler than hotter) Mass 2 x 1030 kg 8x10-2 – 3x102 (more stars less massive than more) Composition 70% Hydrogen, 28% Helium, 2% heavier elements (by percentage of mass) Typical for Pop I, Pop II stars are more metal poor Age 4.8 billion years of an expected 10 billion year lifetime 105 – 1010 yrs, More older stars than younger stars