Our nearest star has woken up for real and for sure. After several years of stubborn silence, the Sun has unleashed several fairly big explosions of material. Called Coronal Mass Ejections, or CMEs, these gigantic events blast out hundreds of billions of tons of matter into space. They create vast interplanetary shock waves, and when they reach the Earth can cause all sorts of havoc. They are different from solar flares, but have similar origins in the Sun's magnetic field.
NASA's recently-launched Solar Dynamics Observatory caught the action mid-eruption. This image shows million-degree-hot gas blasting off the surface, entangled in the Sun's strong magnetic field. The most recent CMEs probably won't do much more than give us pretty aurorae -- they've already been spotted -- which is good (worse effects are the loss of satellites and potential blackouts on Earth). In fact, if you live in the far north or south you may be able to see the light show.
You can read more about this at Orbiting Frog, SpaceWeather (with pictures!), Universe Today, and pretty much every other space blog on the planet. I'm probably too far south and in far too light-polluted skies to see, but give it a try if you can. Aurorae can be quite spectacular.
But if you miss it, don't fret: I'm sure we'll get lots of other opportunities. The Sun is gearing up for the peak of its cycle in the next three years or so, and there will be plenty of chances to watch as our sky reacts.
Image credit: NASA/SDO