On September 1 1859 one of the largest solar flares ever seen was recorded by Richard Carrington. A day later a powerful geomagnetic disturbance was observed, aurorae were seen as far south as Tahiti, and electrical currents were induced in telegraph lines across North America. This, the "Carrington Event", was a consequence of one of the largest coronal mass ejections (CMEs) to strike the Earth in the past 2 centuries.
I will discuss the physics of solar flares and CMEs and their interactions with Earth. The historical record informs us of the frequency with which large CMEs strike the Earth, and observations of flares on other stars let us extrapolate likelihoods of extremely large and rare events. The question of another large CME striking is one of when, not if. The consequences can be devastating for an unprepared society. Are we ready?
Prof. Walter, a resident of East Setauket, studies star birth, stellar weather, and star death using the Chandra and XMM-Newton X-ray observatories, the Hubble Space Telescope, TESS, and telescopes in Arizona, Hawaii and Chile. He has been a professor of Astronomy at Stony Brook since 1989.