The park encompasses more than 6 million acres in a complete sub-arctic ecosystem. It features North America’s highest mountain, 20,320-foot tall Mount McKinley. The aurora is a beautiful, phenomenon, occurring year-round. Only in the fall, winter and early spring, is there enough darkness to allow us to see the northern lights when they occur. The aurora borealis occurs when a coronal mass ejection, a massive burst of solar wind and magnetic fields, interacts with elements in the earth’s atmosphere. Coronal mass ejections are often associated with other forms of solar activity, most notably solar flares.