What causes or triggers the earths auroras (the Northern and Southern Lights)? The Earths fast plasma jet causes spacequakes and these trigger the aurora, also known as the Northern Lights (Southern Lights are called the Aurora Australis). Although the Solar plasma wind is part of the process, the solar wind is not the the only cause of auroras being seen in our skies.
Earths natural Neon light show
The cause of the aurora is electrically excited or charged atoms, molecules and ions emitting photons (light). It is a natural version of Neon lights. How the aurora creating atoms get electrically charged and are accelerated towards earth (against the solar plasma wind) is due to the process that creates earths spacequakes.