The center is a division of the National Oceanic and Atmospheric Administration. Forecasters there monitor solar activity, measure disturbances in Earth's magnetic field, and track reports of everything from intense auroras to satellite-communications disturbances.

In addition to providing a celestial show, which was reported by observers as far southwest as Colorado, the storm caused power fluctuations in the generating systems of all major electricity producers in the Northeast, Murtaugh said.

"We know that all the power companies, for the most part, in the East and the Northeast were affected," he said, noting that the Space Environment Center received reports of power surges from electricity companies from Pennsylvania to Maine.

Forecasters traced the cause of the magnetic storm -- the strongest in more than a year -- to an ejection of material from the sun's surface last Sunday night.

Two Internet websites that track aurora activity were today full of reports from those lucky enough to witness the colorful show.

An observer from Ipswitch, South Dakota called the show "Amazing!" and wrote that at 5 a.m. green light filled the entire north horizon and extended almost directly overhead.

First beams were shooting up, "then balls of light shooting up, then curtians of light like pouring over an upside-down water fall. One burst of red light, Very bright green (with) white prevalent lines in beams, balls fuzzy bomb explosions flying across the sky," the viewer wrote.

Another observer in Syracuse, New York, described the spectacle as a "nice aurora curtain with bright vertical streamers. Lots of white with traces of green early on, then finishing up with bright red off in the east-northeast horizon.

"There were vibrant pulsations from the middle of the curtain up to near the zenith," the observer wrote.

While the affects of the storm may still be influencing Earth into Friday evening, the severe affects had mostly subsided by midday Friday, Murtaugh said.