Kicking off with a spectacular CME or coronal mass ejection on Sunday, the sun has been in the grip of a massive magnetic storm. This is the most intense solar storm in the current solar cycle, Cycle 24, which was supposed to have peaked in 2013. The sun’s radiation fluctuates, following an 11-year cycle. The unexpectedly strong storm was rated as a G4 geomagnetic storm by the National Oceanic and Atmospheric Administration’s Space Weather Center.
A CME consists of a mass of energized gas bubbles from the corona, the sun’s superheated atmosphere, surrounded by a magnetic field. Depending on its direction and speed, a CME can disrupt the earth’s magnetic field, knocking out power grids and satellite communications temporarily. On Sunday March 15, two CMEs joined to form a powerful solar storm directed toward earth. Essentially, earth-directed CMEs bring plasma or ionized gas, as much as a billion tons, into contact with the earth’s magnetic field.
Space weather, resulting from fluctuations in the solar wind and the sun’s magnetic field, is not very well understood, and at present, difficult to predict. Luckily, the G4 solar storm does not endanger satellites or astronauts in space. As of Wednesday, March 18, the solar storm was subsiding but some more episodes may be possible.
The March 15 CME produced spectacular aurora displays, turning the sky brilliant green on St. Patrick’s Day. At a press teleconference, Brent Gordon, of the Space Weather Prediction Center’s space weather services said: “”We have heard of some very vivid sightings of aurora before the sun rose today. Aurora sightings were mainly confined to the northern tier of the United States — Minnesota, Wisconsin, both North and South Dakota as well as Washington State … and of course Alaska as well.”
Amateur astronomers have been posting pictures of the spectacular displays, seen in the United States, Europe, Australia and New Zealand, over at earthsky.org. Aurorae are the result of geomagnetic activity, visible in the night sky. They are caused by the collision of atmospheric gases with charged particles. Seen in the northern hemisphere, they are known as aurora borealis, and in the southern hemisphere, as aurora australis.
