Space weather

Space weather is variation in the Sun and the space environment around Earth, including the solar wind, magnetosphere, and ionosphere. It can disrupt technology and affect human activities in space and on Earth.

Solar wind: A continuous flow of charged particles escaping from the Sun's outer atmosphere. Its speed, density, and embedded magnetic field carry solar disturbances toward Earth.
Space weather forecasting: Prediction of solar activity and its effects on the space environment and technological systems. Forecasts provide warning time for radiation, geomagnetic, and radio disruptions.
Carrington Event: The exceptionally intense geomagnetic storm of September 1859, associated with a major solar eruption. Its telegraph disruptions revealed that solar disturbances could affect technology on Earth.
Power grid: An interconnected system for generating, transmitting, and distributing electrical power. Geomagnetically induced currents can disrupt transformers and grid operations.
Solar dynamo: The process by which motion in the Sun's electrically conducting plasma generates and maintains magnetic fields. Its changing magnetic fields underlie solar cycles and the activity that drives space weather.
Coronal mass ejection: A large expulsion of magnetized plasma from the Sun's corona into interplanetary space. Earth-directed ejections can deliver the strongest geomagnetic storm drivers.
Geomagnetically induced current: An electric current induced in long conductors by changing geomagnetic fields. These currents can overload power grids during strong geomagnetic disturbances.
Solar flare: A sudden, intense release of energy and radiation from the Sun's atmosphere. Flares provided early evidence that solar eruptions can rapidly disturb Earth's upper atmosphere.
High-frequency radio communication: Radio communication using frequencies that can reflect from the ionosphere over long distances. Solar flares and ionospheric disturbances can weaken or interrupt these signals.
Solar cycle: The roughly 11-year cycle in the number and magnetic character of sunspots and related solar activity. Cycle phase changes the background likelihood of flares and eruptions, but not their precise timing.

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