On January 13, the National Weather Service’s Space Weather Prediction Center issued a scary-sounding news flash. “ALERT,” it said. “Type IV Radio Emission.” If that was too arcane-sounding to get you spooked, there was this detail that followed: type IV emissions usually result from a major eruption on the Sun.
That is exactly what had happened. The Sun is currently entering the peak of its 11-year cycle of magnetic activity. When that happens — the actual peak comes in 2013 — its surface becomes blotchy with sunspots, its luminosity grows fractionally brighter, and it sends giant flares up in sweeping arcs above the solar atmosphere. Every so often, it also ejects a blob of hot, charged particles speeding into space.
Typically, we don’t have much to fear from these kinds of events, but the January 13 blob, known more formally as a coronal mass ejection, or CME, was blasted more or less directly toward Earth, at about a million m.p.h. (1.6 million k/h). In principle, that could have led to a disaster. When a mass of charged particles slams into our planet’s magnetic field, it can send jolts of electromagnetic energy shooting in all directions, causing what’s known as a geomagnetic storm that can threaten communications satellites and radio transmissions, and even trigger blackouts like the one that struck Quebec in 1989 when a CME zapped a regional power grid. On the plus side, geomagnetic storms also tend to trigger amazing displays of the Aurora Borealis — the Northern Lights, to you and me. A CME that passed by last spring, for example, seems to have had that effect.
But like breathless warnings of wintertime blizzards that turn out to be mere flurries, this CME was something of a dud. “We’re not going to be in for a big disturbance,” the Space Weather Prediction Center’s Norm Cohen told MSNBC shortly after the eruption was detected.
Sure enough, when the blob finally arrived on Thursday after covering the 93 million miles (150 million km) between Sun and Earth, the disruption was minimal. “Weak power grid fluctuations may occur,” read that day’s alert. “Minor impact on satellite operations possible.”
(Photos: Window on Infinity: Pictures from Space)
We hadn’t exactly dodged the bullet; instead, the bullet turned out to be made of rubber. The Sun will be crackling with magnetic storms for many months to come, however and may spawn more CMEs or even the fantastic fiery tempests known as solar tornados. The pyrotechnics, in other words, are hardly over — and neither is the danger.