Our sun is an active star that has storms. Sometimes the sun ejects a cloud of gas, called a coronal mass ejection or CME. CMEs are often associated with solar flares, and it takes about two to three days for the charged particles in this gas to reach Earth. Earth’s magnetic field deflects these particles toward the North and South Poles.
Unfortunately, solar electrons and protons from CMEs collide with the Earth’s magnetic field and atmosphere and can stir up electromagnetic storms in the Earth’s magnetosphere. These geomagnetic storms can result in the Northern Lights but also disrupt satellite-based navigation, communications, air travel, power grids and even pipelines. A geomagnetic storm in March 1989 shut down the Hydro-Quebec electric grid in Canada, leaving people without electricity.
In a worst-case scenario, the costs of an extreme geomagnetic storm in the United States could be in the trillions of dollars and would require a recovery period of up to a decade. As a result, the U.S. is developing plans to reliably address impacts of geomagnetic storms on our bulk power system. Networks are being set up across the globe to monitor geomagnetic conditions.
An emerging discipline known as space weather attempts to forecast the effects of solar activity on the upper atmosphere so that impacts to society can be minimized. Instruments on satellites can observe ejections of high-energy plasma from the sun. These can result in NOAA’s Space Weather Prediction Center issuing a warning of a coming magnetic storm, estimating time of arrival and intensity.