Delayed solar blast brings bright auroral show A day late, sun's storm of magnetic energy sweeps safely past Earth

April 12, 1997|By Frank D. Roylance | Frank D. Roylance,SUN STAFF

It arrived a day late, but that blast of magnetic energy that erupted from the sun on Monday has finally blown past the Earth. It triggered changes in the Earth's magnetic field and brilliant auroral displays as far south as Boston, but no reported damage.

Excited scientists at the Goddard Space Flight Center in Greenbelt said the solar storm's impact was first detected at about 8 p.m. Thursday, and continued to be felt for at least 18 hours. Its arrival produced a flood of data from a new fleet of satellites and ground stations.

"It's big for this [quiet] time of the [11-year] solar cycle," said Dr. Nicky Fox, a member of the International Solar Terrestrial Physics Program at Goddard. Its effects will likely be dwarfed as solar activity increases in coming years.

"The big news is that the aurora [Northern Lights] were seen overhead in Boston," she said. "To get aurora to Boston, it had to be a real doozy."

Auroral displays occur when atomic particles racing from the sun are swept up by Earth's magnetic field and drawn toward the poles. When they strike the outer fringes of Earth's atmosphere, the gas molecules glow.

They are rarely seen far from the poles, but powerful solar storms can push them to lower latitudes. A 1989 event produced auroras as far south as Texas.

Thursday night's displays were seen in New Hampshire, Vermont and Wyoming.

At Middlebury College, in west-central Vermont, junior physics major Becky Walldroff, 20, joined scores of students who raced out of their dorms around 10: 30 p.m. Thursday. They watched and cheered the display for hours.

"It stretched from the Adirondacks in the west all the way to the east and the Green Mountains," she said. "It was this neon green color for the most part, and it would sort of fade in and out. And it would send spears of color into the sky.

"At its most spectacular, it shot white spears to the zenith. It would move and shift, and it was fringed in red and yellow. It was quite colorful," Walldroff said. "Most people were amazed."

The federal Space Environment Center in Boulder, Colo., received no reports of problems with communications satellites, electric utilities or pipelines, which can suffer electrical surges and damage as magnetic storms sweep the Earth.

The center rated the disturbances at 15 to 20, on a scale from 0 to 400. The 1989 solar storm -- the largest in 40 years -- caused power outages. It was rated 273.

Dr. Donald Michels, of the Naval Research Laboratory in Washington, said ground stations reported strong fluctuations yesterday in the Earth's magnetic field -- lines of force that surround the Earth like the lines of iron filings around a bar magnet.

"Sometimes the field varies so greatly a compass needle starts gyrating quite a lot," he said. "In the old days, it was seen as quite an evil omen."

The solar storm was triggered by a coronal mass ejection (CME) on the sun at 10 a.m. Monday. A CME is a huge bubble of atomic particles that erupts from the sun's surface and races across the solar system in an expanding shock front at speeds of 1 million or 2 million mph.

Its arrival, first predicted for Wednesday, was apparently delayed by interplanetary "traffic."

"Right in front of the ejecta that came from the sun was an incredibly slow solar wind, and that literally backed it up, like getting through treacle, or molasses."

Solar weather is explained in "Electric Space," an exhibit at the Maryland Science Center.

Pub Date: 4/12/97

Baltimore Sun Articles
Please note the green-lined linked article text has been applied commercially without any involvement from our newsroom editors, reporters or any other editorial staff.