An X1.6 solar flare has erupted from the sun, peaking at 1:48 p.m. EDT on September 10 -- sending radiation barrelling directly towards the Earth at a speed of 2.5 million miles per hour. The resulting geomagnetic, or "solar", storms are expected to hit by September 12 -- the most severe we've seen in a few years. The sun also erupted in two coronal mass ejections -- bursts of magnetic fields and solar winds -- from the same active region.
There have been bigger flares in recent months -- earlier this year we saw an X4.9 flare -- but this particular flare's effects on Earth will be so pronounced because of its location: directly in line with Earth. That doesn't, however, mean the radiation is anything to be directly afraid of: although the incoming storms are classified "moderate" and "strong", the Earth's atmospheric layer, strengthened by the , protects the planet from the blasts of solar radiation.
However, the cloud of material will cause disruptions in the Earth's magnetosphere. This can --and already has -- disrupt radio and satellite communications, as well as navigational equipment. It can also cause damage to satellites and result in power surges that damage power lines and cause power outages.
On a rather lovelier note, it also means a period of increased aurora activity, so if you're in aurora zones (there's a guide to locations and forecasts here on the University of Alaska Geophysical Institute website), get your cameras ready -- there's a good guide on how to photograph the phenomenon on the Australian Space Academy website.