Billions of tons of radioactive solar particles from the sun are headed straight toward Earth, and could arrive by Monday.
The event, known as a Coronal Mass Ejection (CME), was reported by NASA as erupting on Friday March 15 at 2:54 a.m. EDT. CMEs do not always move toward Earth and tend to vary in speed. This particular CME is moving toward our planet at a relatively high rate of 900 miles per second. This means that the eruption will have mild to moderate effects on Earth, potentially effecting satellites in space and on the ground.
"Solar material streams out through the interplanetary medium, impacting any planet or spacecraft in its path," says NASA. "CMEs are sometimes associated with flares but can occur independently."
CMEs should not be confused with solar flares, which occur more frequently. CMEs that reach Earth can result in what's called a geomagnetic storm, caused by the CME connecting with the outside of Earth's magnetic envelope, the magnetosphere, for a long period of time.
NASA observed the event using its Solar Terrestrial Relations Observatory (STEREO) and ESA/NASA's Solar and Heliospheric Observatory (SOHO). The Administration has warned that the CME may impact the Spitzer and Messenger spacecraft, and has notified mission operators. NASA does say, however, that the event is associated with "only minor particle radiation."
If you're worried about radioactive material landing in your backyard, you can rest those fears. Probably the most the CME would affect you would be if it disrupted a nearby power grid, but those are extreme cases.
The official U.S. government source for space weather forecasts, watches, alerts and warnings is NOAA's Space Weather Prediction Center. NASA will continue to provide updates on its website if necessary. You can also visit NASA's Spaceweather Frequently Asked Questions page for more information about CMEs and other space phenomena.