Explosions on the sun regularly disrupt the magnetic envelope surrounding Earth, but that envelope, the magnetosphere, largely protects the surface of the planet itself from space weather with one exception. As a rule, changes in magnetic fields cause electric currents and vice versa, so all that change in the magnetosphere causes electric currents to form on the ground. Called geomagnetically induced currents or GICs, such currents extend some 60 miles underground, electrifying any conductors – power grid lines, or oil pipes, for example along the way.
A big enough electrical surge from a GIC can knock out the transformers in a power grid. Electric companies can protect the grid from such surges by shutting down or lowering the power load on the system, but this, of course, costs money so they also don't wish to be overly cautious by reducing power output unless it is really necessary. New analysis by scientists at NASA's Goddard Space Flight Center in Greenbelt, Md., published online in Space Weather on February 23, 2012, provides some basic guidelines to help model some of the largest, most damaging GICs.
Risk analysis and adequate risk protection both rely on numerous factors. Modeling an extreme, devastating GIC is a crucial part of that picture. Referred to as 100-year events, that is, events so extreme they only happen on average once every 100 years, such currents could cause significant damage to Earth's power grids worldwide. But proper preparation and accurate space weather forecasting could mitigate intense damage, the same way that communities can evacuate or protect their homes if given enough advance warning of a hurricane.
A big enough electrical surge from a GIC can knock out the transformers in a power grid. Electric companies can protect the grid from such surges by shutting down or lowering the power load on the system, but this, of course, costs money so they also don't wish to be overly cautious by reducing power output unless it is really necessary. New analysis by scientists at NASA's Goddard Space Flight Center in Greenbelt, Md., published online in Space Weather on February 23, 2012, provides some basic guidelines to help model some of the largest, most damaging GICs.
Risk analysis and adequate risk protection both rely on numerous factors. Modeling an extreme, devastating GIC is a crucial part of that picture. Referred to as 100-year events, that is, events so extreme they only happen on average once every 100 years, such currents could cause significant damage to Earth's power grids worldwide. But proper preparation and accurate space weather forecasting could mitigate intense damage, the same way that communities can evacuate or protect their homes if given enough advance warning of a hurricane.
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