National Geographic : 2012 Jun
Magnetic field lines Solar wind LAWSON PARKER, NGM STAFF. SOURCE: ERIC DONOVAN, UNIVERSITY OF CALGARY Solar winds compress Earth's magnetic field, elongating the back side into a tail. Energy produced by the interaction of solar winds and Earth's magnetic field pushes electrons down along field lines and into the atmosphere. Electrons excite Earth's atmospheric gases, which give off light and color. Magnetic field lines are continuously broken and dragged over the Poles. The lines reconnect on the back side and move toward Earth to start the cycle again. WHAT CAUSES AURORAS?