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The Sun does more than light the sky—it sends a continuous stream of charged particles, known as the solar wind, racing outward from its corona. Because the corona’s plasma is so hot that solar gravity cannot confine it, the wind flows freely into space, impacting Earth’s magnetosphere and space weather.
Typical solar‑wind speeds hover around 400 km s⁻¹ (≈250 mi s⁻¹), but can reach up to 800 km s⁻¹ (≈500 mi s⁻¹) during coronal mass ejections or coronal holes. At these velocities, the plasma travels the 1 AU (149.6 million km) distance to Earth in roughly 2–4 days. Variability in speed arises from the mixture of fast and slow streams, the composition of the particles, and their interactions as they propagate.
Space‑weather agencies such as NASA’s Solar Dynamics Observatory and NOAA’s Space Weather Prediction Center continuously monitor the solar wind, providing real‑time data that helps predict geomagnetic storms and protect satellites, power grids, and communication systems.
