The Aurora Arc is one of the most iconic shapes of the Northern Lights, and probably the one you picture when you think of them. It's basically a big, beautiful Arc of green color stretching across the night sky — sometimes combined with rays, drapery or other additional shapes.
The Arc appears usually as grey during the low Aurora activity but in most cases is visible as green stretching from east to west on the lower northern horizon. But one thing's for sure: it will always be stunningly gorgeous, usually accompanied by beautiful rippling or flickering lights that will leave you enchanted.
It's important to note that this shape is caused by the Aurora Borealis known as the Northern Lights—which is a phenomenon caused by solar wind activity. Aurora Arcs are simply forms or shapes the lights take.