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The Sun. Structure of the Sun & Solar Activity. Parts of the Sun. Core: enormous pressure & high temperatures cause the fusion of hydrogen into helium ( 15 million ºC). Corona: very hot , creates solar wind , only visible during a solar eclipse (1 million ºC).
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The Sun Structure of the Sun & Solar Activity
Parts of the Sun Core: enormous pressure & high temperatures cause the fusion of hydrogen into helium (15 million ºC) Corona: very hot, creates solarwind, only visible during a solar eclipse (1 million ºC) Photosphere: innermost layer of atmosphere – VISIBLELIGHT (6 thousand ºC) Radiation Zone: energy from the core moves through the radiative zone in the form of electromagneticradiation(2-7 million ºC) Convective Zone: hot gasses move outward, cool, contract, sink, repeat (2 million ºC) Chromosphere: gives off redish light from Hydrogen (4-50 thousand ºC)
Solar Activity (not part of your notes) • The sun is in constant motion. • Parts of the sun rotate faster than others. • The equator moves the fastest, the poles the slowest. • It takes an average of 27 days for the sun to make one rotation.
Solar Activity (Ejections) • Affected by the sunspot cycle • Solar Ejections are when the sun emits atomic particles: • Prominences • Solar Flares • Coronal Mass Ejections (CME’s)
Sunspots Dark areas of the photosphere of the sun, that are cooler than the surrounding areas, and have a strong magnetic field. Caused by magneticfields created through the movement of gasses (rotation and convection). The sunspot cycle lasts 11 years.
Sunspot Cycle Graph 11 years from low to low
Sept 27, 2001 Sept 27, 2008 (200+ days with no sunspots) SUNSPOTS 2008 also experienced a 50 year low in solar wind pressure.
Prominences Huge arches of glowing gasses that connect areas (in the sun’s atmosphere) that have positive magnetic energy to areas with negative magnetic energy. Caused by the same magnetic fields that create sunspots.
Solar Flares • Sudden outward eruption of charged particles • The trigger is unknown. • During a peak , 5-10 can occur in one day • Particles that escape will increase the strength of the solar wind.
Coronal Mass Ejection Particles (or parts of the corona) are thrown off the sun. Strike Earth’s magnetosphere creating disturbances called geomagneticstorms. Geomagnetic storms can disturb radio communication, damage satellites and cause auroras.
Earth Earth’s Magnetosphere
Earth’s Magnetosphere A magnetic field surrounding the earth – affected by solar wind and the magnetic fields of other space objects. Protects the majority of the Earth from the solar wind. Solar wind is a stream of electrically charged particles (protons & electrons) flowing from the sun.
Computer Animation of a CME creating Auroras on Earth – notice Earth’s magnetosphere. (Wait for animation to start )
Geomagnetic Storm Effects • Radiation Hazards to humans– especially those in space • Migratory animals less able to navigate (esp. homing pigeons) • Communication Disruptions: ground-to -air, ship-to-shore, shortwave, broadcast, and amateur radio.
Geomagnetic Storm Effects • GPS & Loran navigationdisruptions • Satellite hardware damage • Power Grid Outages – 1989 Quebec & NE US was out for 9 hours (affecting 6 million people)