Sun delivers yet another shot at Earth
Sky watchers awed by colorful light shows
By Kate Tobin and Richard Stenger
(CNN) -- As Earth's magnetic field weathered a strong solar shock wave on Wednesday, the sun unleashed another powerful flare that could trigger more geomagnetic storms on Thursday.
The first cloud of electrified solar gas began buffeting our planet's magnetosphere before dawn EST Wednesday, generating bright auroras, jolting power grids and stunning a handful of satellites.
Our planet managed to endure the brunt of the Wednesday storm, unleashed Tuesday by the third most powerful solar flare, without major problems.
But late Wednesday, solar scientists observed another big solar explosion, one of the top 20 on record, which directed another huge cloud of supercharged gas in our direction.
"This is also a very fast one," said European Space Agency solar scientist Paal Brekke. "It could arrive already tomorrow afternoon or evening if it does not slow down."
Whether it shakes up the planet more or less than the Wednesday storm will not be known until it arrives and depends on a variety of factors, like its magnetic alignment and whether it delivers a glancing blow or direct hit.
Meanwhile, the current storm is expected to produce strong to severe geomagnetic conditions to persist throughout the day and abate early Thursday.
"We're not out of the woods yet," said David Zeezula of the National Atmospheric and Oceanic Administration's Space Environment Center.
Power grids in the northern United States and Canada are feeling the effects of the storm. Utilities have endured power surges and are closely monitoring their systems and taking protective measures to prevent surges, according to NOAA.
Yet so far only sporadic problems have been reported. One Japanese satellite was knocked offline this weekend, possibly due to electrical problems connected with increased solar activity.
Some instruments onboard the Solar and Heliospheric Observatory (SOHO), a sun-watching satellite, have been turned off to prevent malfunctions.
And some airplanes flying in extreme northern latitudes, mostly over the Arctic, have had minor problems with radio communications, according to Canadian aviation authorities. But no flights have been stopped and the pilots could use backup radio systems in an emergency.
"It's causing interference, in some cases more severe than others. Overall, it is still a very manageable occurrence from an air traffic point of view," said Louis Garneau, spokesman for Nav Canada, which manages Canada's civil aviation navigation service.
Quivering and quaking
Solar flares are often associated with coronal mass ejections, or CMEs, like the one that arrived Wednesday. Usually CMEs need several days to make the trip of 93 million miles, but this one made the journey in 19 hours, according to space weather scientists.
"This CME hit the Earth's magnetic field. Like a bubble, it's shivering, quaking. It will probably continue to quiver throughout the day and night," said Tony Phillips of the NASA Web site SpaceWeather.com.
When high-energy solar winds from a CME interact with the magnetosphere and generate a geomagnetic storm, they can boost the northern and southern lights considerably, pushing them from the polar regions to the middle latitudes.
Early Wednesday, sky watchers as far south as El Paso, Texas, were rewarded with nature's nocturnal neon.
"Wow! What a show! The colors were very vivid to the naked eye," gushed Jimmy Westlake, an astronomy professor from Steamboat Springs, Colorado.
Astronauts take cover
Nevertheless, NASA has taken precautions as well with its most precious cargo, astronaut Mike Foale and Russian cosmonaut Alexander Kaleri on board the international space station.
Foale and Kaleri, the only humans currently outside the protection of Earth's atmosphere, are retreating during peak exposure times to the living quarters of the station, which provides the best radiation protection.
As a precaution, NASA shut down the station's robotic arm, which is the most exposed piece of hardware.
Researchers classify solar flares using three categories: C for weak, M for Moderate and X for strong. Tuesday's solar outburst was classified an X17.2.
The largest flare on record, one of two known X20s, occurred on April 2, 2001, but was not directed at Earth.
Space weather forecasters say this spate of strong solar flares is not consistent with normal solar behavior. The sun, which follows an 11-year activity cycle, has been quieting down since the last peak in 2000.
CNN space Producer David Santucci contributed to this report.