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Solar storm in the forecast; celestial light shows expected

E-mail|Link|Comments () August 3, 2010 05:06 PM

NASA

An extreme ultraviolet photo from NASA -- a light show in itself -- shows the sun's northern hemisphere in mid-eruption.

By Martin Finucane, Globe Staff

If you're driving in the wee hours of Wednesday or Thursday morning and you see beautiful red and green curtains waving against the sky, there's no need to check your eyesight or your sanity.

Scientists say the Northern Lights may be visible in areas farther south than they are normally, due to eruptions on the surface of the sun.

Early Sunday morning, the eruptions blasted plasma, or ionized atoms, into space and it began traveling towards Earth at about a million miles per hour, according to experts from the Harvard-Smithsonian Center for Astrophysics.

When the plasma from the "coronal mass ejection" reaches Earth, it will interact with our planet's magnetic field, potentially creating a geomagnetic storm in which solar particles collide with nitrogen and oxygen atoms and glow like neon signs, the scientists said.

Normally, such light shows are seen only in higher latitudes, where they are called the Northern Lights, or aurora borealis, but during a geomagenetic storm aurorae can light up the sky at lower latitudes. The experts said sky watchers should look to the north to see the phenomenon.

The latest estimates are that the plasma will arrive in four waves, one at 3 a.m. Wednesday, one at 1 p.m. Wednesday, one at 8 p.m. Wednesday, and one at 2 a.m. Thursday, said David Aguilar, a spokesman for the Harvard-Smithsonian center.

There is a three-hour window of uncertainty both before and after those target times, he said, because the speed of the waves is not constant.

"They're like giant hurricanes. They're large and fuzzy and they're moving along. They're not like railroad trains in Europe that run on time," he said.

He said the first wave was the most powerful, but depending on the earth's magnetic field, any of the four waves could produce a spectacular light show.

The aurorae will likely not be visible during the daylight hours or to city residents, so those who want to see them would do best to get away from urban light pollution and plan to stay up late.

Besides the potential for causing the northern lights, this solar event signals that after a long quiet spell, the sun may be returning to a heightened period of activity, the Globe reports today.