A Scary 13th: 20 Years Ago, Earth Was Blasted with a Massive Plume of Solar Plasma [Slide Show]
Violent space weather treated many to a fantastic display of colorful auroras, but damaged power grids left six million Canadians in the dark
Credits: SOHO/EIT (ESA & NASA)
THE VIEW FROM ABOVE A crew member on board the space shuttle Discovery took this shot of the aurora australis (southern lights) in 1991. Such photos are difficult to take because they require special film that can only be used on short-duration orbital flights; space radiation can ruin the imaging material on longer missions. Similarly, astronauts, especially spacewalkers, must take precautions during periods of heightened solar activity to limit exposure to tissue-damaging radiation.
VULNERABLE Even more powerful than the March 13, 1989, incident was the geomagnetic superstorm of 1859 called the Carrington event, named after the English astronomer who noticed bright flashes from the sun as he counted sunspots. Telegraph services in many parts of the world failed and auroras glowed as far south as Cuba. As the use of electricity-fueled technologies has spread since then, society has grown immensely more prone to space weather disturbances. Another blistering geomagnetic storm, though only packing about two-thirds of the Carrington event’s punch, was the one that struck in May 1921. It sent currents through the ground 10 times as strong as those that disrupted Quebec's power grid, though again the electrical infrastructure then paled in comparison to the complexity and interdependence of today’s. This map indicates where a 1921-type storm would cripple electrical power distribution in the U.S. now. Some 130 million might be left without power: no lights, refrigeration, air-conditioning or heating—and no Internet.... You get the picture.
John Kappenman/Metatech Corporation
NORTHERN LIGHTS--OUT Geomagnetic storms can trip up power distribution, and none have (yet) more dramatically than the March 13, 1989, event that left six million Canadians without electricity. Starting at 2:44 A.M. local time, a cascading series of failures at substations knocked out half of Quebec's power generation in less than a minute, says astrophysicist Sten Odenwald in his book The 23rd Cycle. Over longer periods, however, damage to the electrical grid accumulates from repeated, low-level space weather events. So-called geomagnetically induced currents that flow underground can trigger heat spikes in transformers, wearing down their insulation for years until they fail. Better space weather predictions could allow utilities to reduce the power load in the grid so the voltage differentials that trigger failures would not develop, sparing expensive transformers as well as stopping the interruption of electrical service. Oil and gas pipelines also undergo corrosion caused by the electrical static in the soil. To lessen this rusting, some pipelines are now built in segments to reduce the voltage differential over long spans of pipe.
RAGING SUN Looplike solar prominences [bottom right] that erupt from the sun's surface—occasionally for days on end—can sever, launching a coronal mass ejection (CME), although CMEs can burst forth of their own accord, as well. These massive bubbles of gas and tangled magnetic field energy are the source of most major space weather events that threaten Earth. According to a 2008 National Academy of Sciences report, a CME must meet three criteria to whip up a powerful geomagnetic storm: It must shoot from near the sun's mid-latitudes on the plane of Earth's orbit so as to be on a trajectory toward our planet; have great size and speed, and thereby significant energy; and have a powerful magnetic field oriented opposite that of Earth's, which would allow the storm to negate Earth's field and unleash its full, disruptive potential.
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SUNBURST, AND A NEAR MISS Flares flash from the sun and send bursts of energy and matter flying at Earth. The most massive solar flare ever recorded broke from the sun's surface on November 4, 2003, during a tumultuous season popularly known as the Halloween storms. A coronal mass ejection (CME)—a great blob of superheated, ionized gas—billowed out from the sun into space afterward. Fortunately, given the CME's point of origin on the right-hand side of the sun—respective both to Earth and to the Solar and Heliospheric Observatory (SOHO) satellite that tracked it—our planet took only a glancing shot and not a direct hit, according to the European Space Agency. But the economic damage was still considerable: Transformers failed in Sweden, causing a blackout; airlines rerouted high-altitude flights to avoid instrument failure at a cost of tens of thousands of dollars apiece; and a $640-million Japanese science satellite's circuits overloaded and went dead. NASA told astronauts on board the International Space Station to take shelter in the section of the orbiting facility with the thickest shielding against radiation, according to a 2004 National Oceanic & Atmospheric Administration report.
SOHO/EIT (ESA & NASA)
MAGNETIC SHIELDING Life could not exist on Earth were it not for the deflection of solar radiation and plasmas by the magnetic field generated by the planet's molten iron core. Solar wind—the constant stream of particles emitted by the sun into space—contours the Earth's field like water flowing around an object. The magnetic field lines bend behind the planet and periodically "reconnect," snapping back and unleashing solar substorms that flood the atmosphere at Earth's polar regions with charged particles, producing brilliant, dancing auroras. Major fluxes of energy, magnetism and particles contained in coronal mass ejections can batter the magnetosphere and cast auroras toward the equator. (The image is not to scale—Earth's diameter is a hundredth of the sun's and it orbits at an average distance of some 93 million miles, or 150 million kilometers.)
COLORFUL PORTENTS An eyewitness snapped this aurora shot in Ontario, Canada, the night of the 1989 event. Highly charged and magnetized particles from the sun colliding with molecules in Earth's atmosphere produce these crimson, green and magenta ribbons in the sky. Called the aurora borealis (northern lights) and aurora australis (southern lights), after the polar regions where they typically appear, these auroras can also energize the atmosphere over Earth's mid-latitudes during massive geomagnetic storms. Auroras make the sky glow and often undulate overhead like curtains caught in a breeze that is actually Earth's magnetic field; they usually extend from east to west across the sky. Their presence above indicates where electrical currents flow through the ground underfoot. Because the currents cover large swaths of land, they are diffuse and cannot be felt by observers. But transformer stations, power lines and even oil pipelines can be damaged.
EARTH ALIGHT The geomagnetic storm of March 13, 1989, knocked out power to six million people, although it provided quite a light show in the process. The green globe [left] shows the gigantic aurora over Antarctica as seen from the now-defunct Dynamics Explorer 1 satellite on March 14. The image at right overlays the Antarctic aurora data over the Northern Hemisphere's magnetic field lines to indicate how it might have appeared to the satellite's instruments. Flecks of aurora reach into the mid-latitudes, as far south as Texas and Florida, where startled witnesses reported seeing mysterious colors in the night sky. The more powerful a geomagnetic storm, the farther its atmospheric display spreads from the poles to the lower latitudes.
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