This animation of the sun spitting out a coronal mass ejection on March 15, 2013 is based on images captured by the Solar Heliospheric Observatory. In the images, a disk was placed over the sun to better see the dimmer atmosphere around it, called the corona. (SOURCE: ESA and NASA/SOHO. And a hat tip to Earthsky.org for finding it!) Updated below, with a new image. Billions of tons of solar particles are racing through space and headed for Earth. Known as a coronal mass ejection, or CME, the particles erupted from the surface of the sun on Friday. As I write this on Saturday night, the Space Weather Prediction Center is saying that they will reach Earth imminently. That means if you're reading this between Saturday night and early Sunday morning, and you're in the northernmost tier of states (including as far south as New York or Idaho), or in Canada for that matter, you may be treated to a display of Northern Lights, clear skies permitting.
Update: Since I first posted this story, the aurora has, in fact, been visible in the Lower 48 states. The Mt. Washington Observatory has posted a number of wonderful images to its Facebook page, including this one:
The Northern Lights, as seen from the summit of Mt. Washington early on Sunday, March 17, 2013. Click on the image to go to the Mt. Washington Observatory Facebook page, where you'll find more imagery. (Source: Mount Washington Observatory)
For more photos like this one, head on over to the Mt. Washington FB page.
According to the Space Weather Prediction Center, the the coronal mass ejection is also expected to trigger moderate geomagnetic storms on Sunday (March 17th). These are disturbances in Earth's magnetic field, and they can affect power systems and spacecraft operations. Lastly, check out this awesome animation from NASA's Goddard Spaceflight Center, which will take you on a journey from the center of the sun to eruptions on the surface and all the way to Earth — click on it to launch it: