A strong geomagnetic storm heading toward earth is expected to create brilliant aurora displays visible as far south as some Lower 48 states beginning late Wednesday night, according to National Atmospheric and Oceanic Administration.
The storm is a result of an X-class flare on Jan. 7, a powerful burst of radiation from the sun. Solar flares accompanied by a coronal mass ejection (CME) -- a giant cloud of solar particles that erupts from the sun -- can prompt increased aurora when it reaches Earth. The recent flare launched such a CME in Earth's direction. Harmful radiation can't pass through the planet's atmosphere enough to affect Earthlings, but the flares can cause electrical and magnetic disturbances.
The National Oceanic and Atmospheric Administration rates the storm heading toward Earth as a "G3" -- a strong storm that may affect satellite navigation, could cause satellite orbits to drag, and could falsely trigger some alarm systems. The strongest NOAA rating is a G5, an "extreme" storm.
During storms of strong magnitude, aurora has been spotted as far south as Illinois and Oregon, NOAA writes. Displays low on the horizon from Seattle to Cleveland, Des Moines, Iowa and Boston are being forecast by the University of Alaska Fairbanks Geophysical Institute aurora forecast center. NOAA National Weather Service Space Weather Prediction Center also posted a map on its Facebook page outlining how far south the displays may be visible.
The storm will reach earth sometime between 10 p.m. Wednesday and 1 a.m. Thursday Alaska time. Activity will remain at strong storm levels through the afternoon of Jan. 9, and will downgrade from moderate to minor storm levels by midnight on Jan. 10. Aurora is expected to be visible across Alaska on Jan. 10.
Accompanying the geomagnetic storm is a solar radiation storm expected to reach moderate levels. Radiation hazard avoidance is recommended for astronauts. NOAA cautions on its Facebook page: "If you were planning to do a space walk in the next few days, it would probably be a good idea to postpone!"
The storm may also create an elevated radiation risk for passengers and crew in high-flying aircraft at high latitudes.
To view the aurora, seek out a location away from light pollution. Traditionally, a good time for viewing is between 11 p.m. and 2 a.m., but during strong solar storms, aurora can be seen at all hours after the sky darkens. Aurora viewing is weather-dependent -- so be sure to check out your local forecast.