Aug 11 2014
On September 1, 1859, a massive solar flare struck the Earth, resulting in beautiful auroras but also inducing currents in telegraph wires causing them to spark and start fires. Hours earlier amateur astronomer Richard Carrington was observing the sun and noticed large sunspots giving off a brief bright flare. In 1859 the telegraph was about the only electric infrastructure we had. What if a Carrington-type event struck today?
Solar flares result from the complex magnetic fields of the sun. Gas in the sun is so hot the electrons are stripped from the hydrogen, resulting in a plasma. Since plasma is therefore made from ions, it carries an electric charge, and when electric charges move they generate a magnetic field. Magnetic fields further induce electric current.
Sometimes the magnetic fields near the surface of the sun interact in such a way that they give off an explosion of energy, called a solar flare. There is also something called a coronal mass ejection, in which a bubble of hot gas erupts from the sun’s corona in a fashion similar to a solar flare. CMEs and solar flares often occur together, but not always, and their causal relationship is not clear.