Don't set your Google Inactive Account Manager just yet, but there are billions of tons of solar matter hurtling toward the Earth at more than 600 miles (970 kilometers) per second. NASA estimates the plasma will hit our atmosphere late Friday night, U.S. Eastern Daylight Time.
This CME (coronal mass ejection) isn't likely to do anything but make the Aurora Borealis more spectacular, so there's not much point in immediately preparing your Google account for the big sign-off. But a solar flare that accompanied the spewing of electrified gas did knock out some radios early Thursday, and there could be more dramatic solar events coming later this year.
Thursday's flare was the biggest so far for 2013, a year that is due to end with the climax of a regular 11-year cycle of solar activity, according to Alex Young, associate director for science in NASA's heliophysics division.
The flare, which peaked at 3:16 a.m. Eastern time in the U.S., would have affected radios in the part of the world that was in daylight then, Young said. Flares typically affect GPS (Global Positioning System) and some aviation and shipping radios, as well as shortwave systems such as amateur radio, he said. NASA doesn't log anecdotal reports of radio failures, but blackouts typically mean a temporary total loss of signal. "It's pretty much a full disruption," Young said.
The flare's magnitude was M6.5, about ten times less powerful than so-called X-class flares, which at their worst can knock out radios for hours, Young said. The radio blackout was rated R2 on a scale from R1 to R5, so it probably lasted tens of minutes, he said.
Flares are caused by sudden releases of pent-up energy from sunspots, which are areas on the Sun where its magnetic fields are highly concentrated.
"It's just a huge flash of light that covers everything from radio waves to gamma rays, and the amount of energy that's released in that flash can be upwards of the equivalent of, say, a billion atomic bombs," Young said.
Solar events big enough to affect communications or power grids on Earth can happen at any time, but the Sun is nearing a so-called "solar maximum" when they are more common, Young said. Flares, CMEs and other solar "weather" is caused by releases of pent-up energy from sunspots, which are concentrated magnetic fields in the Sun,
If they're big enough, these fireworks can cause hours-long radio blackouts, knock out satellites and even affect pipelines and power grids, Young said. In 1989, a CME caused a "geomagnetic storm" around the Earth that took Quebec's power grid offline for about nine hours. The atmosphere shields humans on Earth from the bursts of rays and particles, but they can be unhealthy for astronauts on the International Space Station.
Fortunately, it's possible to predict CMEs because they take at least 15 to 18 hours to travel to Earth, Young said. Power companies watch solar weather closely, and if a very large CME were detected, they might shut down parts of their power grids to prevent overloads and permanent damage, he said.
"Having a big one is inevitable," Young said. Whether it's going to happen tomorrow, or 100 years from now, or even 1,000 years from now, that's a much harder question to answer."