2 (c.a.) Sun's energy, Sunspots and flares
The sun is a ball of glowing gas through and through. The sun’s energy comes from nuclear fusion. About three fourths of the sun’s mass is hydrogen and one fourth is helium.The sun produces an enormous amount of energy in its core, or central region. This energy is not produced by burning fuel. Rather, the sun’s energy comes from nuclear fusion.
Features on or just above the sun’s surface include sunspots, prominences, and solar flares.
Sunspots: Early observers noticed dark spots on the sun’s surface. These became known as sunspots. Sunspots are areas of gas on the sun’s surface that are cooler than the gases around them. Cooler gases don’t give off as much light as hotter gases, which is why sunspots look darker than the rest of the photosphere. Sunspots seem to move across the sun’s surface, showing that the sun rotates on its axis, just as Earth does.
Prominences: Sunspots usually occur in groups. Huge, reddish loops of gas called prominences often link different parts of sunspot regions.
Solar Flares: Sometimes the loops in sunspot regions suddenly connect, releasing large amounts of magnetic energy. The energy heats gas on the sun to millions of degrees Celsius, causing the gas to erupt into space. These eruptions are called solar flares. Solar flares can greatly increase the solar wind from the corona, resulting in an increase in the number of particles reaching Earth’s upper atmosphere. Normally, Earth’s atmosphere and magnetic field block these particles. However, near the North and South poles, the particles can enter Earth’s atmosphere, where they create powerful electric currents that cause gas molecules in the atmosphere to glow. The result is rippling sheets of light in the sky called auroras.
Solar wind particles can also affect Earth’s magnetic field, causing magnetic storms. Magnetic storms sometimes disrupt radio, telephone, and television signals. Magnetic storms can also cause electrical power problems.
Features on or just above the sun’s surface include sunspots, prominences, and solar flares.
Sunspots: Early observers noticed dark spots on the sun’s surface. These became known as sunspots. Sunspots are areas of gas on the sun’s surface that are cooler than the gases around them. Cooler gases don’t give off as much light as hotter gases, which is why sunspots look darker than the rest of the photosphere. Sunspots seem to move across the sun’s surface, showing that the sun rotates on its axis, just as Earth does.
Prominences: Sunspots usually occur in groups. Huge, reddish loops of gas called prominences often link different parts of sunspot regions.
Solar Flares: Sometimes the loops in sunspot regions suddenly connect, releasing large amounts of magnetic energy. The energy heats gas on the sun to millions of degrees Celsius, causing the gas to erupt into space. These eruptions are called solar flares. Solar flares can greatly increase the solar wind from the corona, resulting in an increase in the number of particles reaching Earth’s upper atmosphere. Normally, Earth’s atmosphere and magnetic field block these particles. However, near the North and South poles, the particles can enter Earth’s atmosphere, where they create powerful electric currents that cause gas molecules in the atmosphere to glow. The result is rippling sheets of light in the sky called auroras.
Solar wind particles can also affect Earth’s magnetic field, causing magnetic storms. Magnetic storms sometimes disrupt radio, telephone, and television signals. Magnetic storms can also cause electrical power problems.
