SOMETIMES the sun burps. It flings off mighty arcs of hot plasma known as coronal mass ejections (CMEs). If one of these hits Earth it plays havoc with the planet’s magnetic field. Such storms are among the most spectacular examples of what astronomers call space weather, a subject to which a session at this year’s meeting of the American Association for the Advancement of Science (AAAS), in Boston, was devoted. A big CME can have profound effects. In 1859, for instance, a CME subsequently dubbed the Carrington event, after a British astronomer who realised its connection with a powerful solar flare he had observed a few days earlier, generated auroras that could be seen in the tropics. Normally, as the names “northern” and “southern” lights suggest, such auroras (pictured above) are visible only from high latitude. More significant, the Carrington event played havoc with Earth’s new telecommunications system, the electric telegraph. Lines and networks failed, and some operators received severe shocks.
Today, the damage would be worse. A study published in 2013 by Lloyd’s, a London insurance market, estimated that a Carrington-like…Continue reading
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