A Yukon Aurora.

Last week was another good week for auroras . The story began about two weeks ago when two large Coronal Mass Ejections exploded off the Sun . Waves of elementary particles and ions swept out past the Earth on September 28 and 29, causing many auroras . A week ago, a flapping sheet that divides north and south regions of the Sun's magnetic field passed the Earth, again causing auroras. Pictured above is a particularly good image of one of the October 1 northern lights . Taken in Canada 's Yukon , the city lights of Whitehorse are seen below dark cloud s and a twisting green aurora .