A solar flare, the largest observed over the last years, around mid-February, has produced visible effects on Earth. One of the observable effects are the variations in the secondary cosmic ray flux hitting the Earth, also known as Forbush decreases. Such variations are usually monitored by neutron monitors located throughout the world. For the first time, such variation has been observed by one of the muon telescopes of the Extreme Energy Events (EEE) Project, installed and working since a few years in our Department of Physics/INFN Section in Catania. The Forbush decrease was observed slightly after midnight on February 17th. The value of the cosmic ray flux reached its minimum - with a variation in the order of 3% of the total flux - about 36 hours later, recovering to its standard values within the next days.

Info: http://oldweb.ct.infn.it/~riggi/BRILLAMENTO-SOLARE.pdf