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What could be happening on the Sun right now, and why is it important?
Event Examples Communications, navigation, & radio difficulties? Damage satellites? Threaten power grids? Danger to astronauts or pilots? Cause flow of currents in pipelines? Generate auroras? Affect racing pigeons or other animals? Contribute to global warming?
Sunspots Sunspot cluster

Coronal Mass Ejections (CMEs) CME (movie) X X X X X X Anything over 150 in geomagnetic activity, or 4 in local 'K' index figures
Solar flares X-ray Flare only X and M class flares only X and M class flares

Strong solar winds Solar Wind X X X X X X X
Filaments/prominences Filament

Coronal Holes Coronal hole

Change in solar irradiance

Eclipse Solar eclipse

Sungrazing comets SOHO Comets

Planetary alignments 2 planets

Mercury or Venus Transit Mercury Transit (movie)

Solar disturbances can cause:

  1. Geomagnetic Storms -- disturbances in the geomagnetic field caused by gusts in the solar wind that blows by Earth.
    Causes: Coronal Mass Ejections (CMEs)
    Affects: power systems, spacecraft operation, radio propagation, navigation, migratory animals, auroras
    Scale & measurements: Geomagnetic Storm Scale ("A" index values range from 0 to 400 Nanoteslas; K & Kp index values range from 0 to 9, anything over 5 can have effects on Earth)

  2. Solar Radiation Storms -- elevated levels of radiation that occur when the numbers of energetic particles increase.
    Affects: radiation hazard to astronauts & high-flying planes, satellite operations, communications systems
    Scale & measurements: Solar Radiation Storm Scale (proton/ion flux levels; anything over 10 can have affects on Earth)

  3. Radio Blackouts -- disturbances of the ionosphere caused by X-ray emissions from the Sun.
    Causes: M-class and X-class solar flares
    Affects: high frequency radio, navigation systems
    Scale & measurements: Radio Blackouts Scale (based on x-ray brightness; only M- and X-class flares can affect Earth)
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