Solar flares scheduled to pound Earth

Washington -- The largest solar flare in five years is racing toward Earth, threatening to unleash a torrent of charged particles that could disrupt power grids, GPS and airplane flights.

The sun erupted Tuesday evening, and the effects should start smacking Earth around 4 a.m. PST today, according to forecasters at the federal government's Space Weather Prediction Center. They say the flare is growing as it speeds outward from the sun.

"It's hitting us right in the nose," said Joe Kunches, a scientist for the National Oceanic and Atmospheric Administration.

The solar storm is likely to last through Friday morning, but the region that erupted can still send more blasts our way, Kunches said. He said another set of active sunspots is ready to aim at Earth right after this.

But for now, scientists are waiting to see what happens today when the charged particles hit Earth at 4 million mph.

The storm is coming after an earlier and weaker solar eruption happened Sunday, Kunches said. This newer blast of particles will probably arrive slightly later than forecasters first thought.

That means for North America the "good" part of a solar storm - the one that creates more noticeable auroras or Northern Lights - will peak tonight. Auroras could dip as far south as the Great Lakes states or lower, Kunches said.

Auroras are "probably the treat we get when the sun erupts," Kunches said.

But there is the potential for widespread problems. Solar storms have three ways they can disrupt technology on Earth: with magnetic, radio and radiation emissions.

The magnetic part of the storm has the potential to trip electrical power grids. Kunches said power companies around the Earth have been alerted for possible outages.

Solar storms can also make global positioning systems less accurate, Kunches said. The storm also can cause communication problems and added radiation around the north and south poles, which will probably force airlines to reroute flights.