By Alan Boyle
The sunspot responsible for setting off a colorful round of northern lights over the past week got off a doozy of a parting shot today, just as it was about to pass around the edge of the sun's disk.
Sunspot 1402 let loose with an X-class flare, the most powerful class of solar outburst, at 1:37 p.m. ET today, and NASA's Solar Dynamics Observatory captured a sequence of ultraviolet images as the blast went out. Fortunately, this one was not directed right at Earth.
SpaceWeather.com says NASA's Goddard Space Weather Laboratory detected a "spectacular" coronal mass ejection blasting away from the sun at 5.6 million mph (2,500 kilometers per second). CMEs send out electrically charged particles that can eventually interact with Earth's magnetic field -- but here again, this particular ejection is not heading directly for Earth. There's a chance that it might strike a glancing blow on Monday or so, sparking another bout of auroral displays.
The National Oceanic and Atmospheric Administration's Space Weather Prediction Center reports that the flare created R3-level radio blackouts at about 1:30 p.m. ET today. That level can result in wide-area loss of high-frequency radio comunication, as well as a temporary degradation of low-frequency GPS signals, but no significant problems came to light immediately. Solar radiation levels are elevated -- which may lead to the rerouting of some airline flights. NOAA's guide to space weather scales explains what's what.