FIGURE 3.5 Solar Dynamics Observatory (SDO) image from August 9, 2011, X7 class flare. An X-class flare began at 3:48 a.m. EDT on August 9, 2011, and peaked at 4:05 a.m. The flare burst from active region AR11263 before it rotated out of view from Earth. The image here was captured by NASA’s SDO in extreme ultraviolet light at 131 Å and at the beginning of the event, just before the satellite sensors were overwhelmed by energetic particles. SOURCE: NASA/Solar Dynamics Observatory/Atmospheric Imaging Assembly; available at


electrically charged particles, supersonic flows and shock waves, explosive release of magnetic energy, and solar-driven winds and tides in Earth’s atmosphere.

Moreover, the Sun, the heliosphere, Earth, and the planets together constitute a coupled and intertwined system. It is a formidable challenge to understand the detailed individual processes that control the space environment, while also accounting for the global couplings among the various interacting members of the Sun-heliosphere-Earth system and their subelements, such as the neutral atmosphere and ionosphere. Significant progress has accrued during the past few decades from observations made by space missions and ground-based observatories and from theories and models developed to explain the observations. However, owing to the complexity of this variable, coupled system, scientists have not yet achieved a sufficiently

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