image: The joint ESA/NASA Solar Heliospheric Observatory captured this series of images of a coronal mass ejection on the morning of April 11, 2013 over the course of 3:48 EDT to 4:36 EDT. Mars can be seen on the left. view more
Credit: ESA & NASA/SOHO/GSFC
The M6.5 flare on the morning of April 11, 2013, was also associated with an Earth-directed coronal mass ejection (CME), another solar phenomenon that can send billions of tons of solar particles into space and can reach Earth one to three days later. CMEs can affect electronic systems in satellites and on the ground. Experimental NASA research models show that the CME began at 3:36 a.m. EDT on April 11, leaving the sun at over 600 miles per second.
Earth-directed CMEs can cause a space weather phenomenon called a geomagnetic storm, which occurs when they connect with the outside of the Earth's magnetic envelope, the magnetosphere, for an extended period of time.
The recent space weather also resulted in a weak solar energetic particle (SEP) event near Earth. These events occur when very fast protons and charged particles from the sun travel toward Earth, sometimes in the wake of a solar flare. These events are also referred to as solar radiation storms. Any harmful radiation from the event is blocked by the magnetosphere and atmosphere, so cannot reach humans on Earth. Solar radiation storms can, however, disturb the regions through which high frequency radio communications travel.
NOAA's Space Weather Prediction Center is the United States Government official source for space weather forecasts, alerts, watches and warnings. NASA and NOAA – as well as the US Air Force Weather Agency (AFWA) and others -- keep a constant watch on the sun to monitor for space weather effects such as geomagnetic storms. With advance notification many satellites, spacecraft and technologies can be protected from the worst effects.