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Solar Flare: A Northern Lights show for North America?

Solar flare - one of the biggest in four years - shot from the sun on Sunday. Scientists predict that a solar flare of this size - and traveling toward Earth - could produce a dramatic light show. Did it?

By Joe / February 16, 2011

This image of the sun, captured by The Solar Dynamics Observatory spacecraft January 28, 2011, shows nearly simultaneous solar eruptions on opposite sides of the Sun, in this photograph released by NASA.



A powerful solar flare, hurled into space when superhot gases erupted on the sun Sunday (Feb, 13), might cause a display of the aurora borealis for parts of the northern United States.

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The sun unleashed the solar flare Feb. 13 at about 12:30 p.m. EST (1730 GMT) from a sunspot region that was barely visible last week. Since then, it has grown in size to more than 62,000 miles (100,000 kilometers) across — nearly eight times the width of our Earth.

The flare was categorized by the NOAA Space Weather Prediction Center in Colorado as a Class M6.6 and is the strongest solar flare observed in 2011. It could ramp up northern lights displays for skywatchers living in northern latitudes and graced with clear skies.

Such a flare, covering more than 1 billion square miles of the sun's surface (called the photosphere), was described as "moderate" in intensity. Class M flares are stronger than the weakest category (Class C). They are second only to the most intense Class X solar flares, which can cause disruptions to satellites and communications systems and pose a hazard to astronauts in space.

NOAA's Prediction Center has forecast the possibility of additional solar flares from the same sunspot region over the next two or three days.

Sun flares are gas pains

Solar flares appear to be caused by a sudden release of magnetic energy. The flare itself occurs in the solar atmosphere, generating a brilliant emission of visible light, as well as ultraviolet waves and powerful X-rays.

With major flares there is a disruption of radio communications shortly after the eruption. Indeed, Sunday's eruption produced a loud blast of radio waves that was heard in shortwave receivers around the dayside of our planet.

But solar flares also can act as a type of explosion that sends streams of electrons and protons out into space. These electrons, protons and other particles are hurled out of the sun's magnetic field in a wave of electrified gas.

As these electrons and protons come into contact with the Earth's magnetic field and stream toward the magnetic poles, the chance of a collision between these charged energy particles and the rarefied gases of the upper atmosphere increases dramatically, producing a disturbance, or "magnetic storm," in the Earth's magnetic field.

Along with causing additional disruptions to radio communications, a magnetic storm might also prompt a view of the aurora borealis, or northern lights, across parts of the northern United States.


For the latest aurora forecasts, visit the Geophysical Institute at the University of Alaska, Fairbanks.

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