6. Northern and Southern Lights (Aurora Borealis and Australis)
The auroras—better known as the Northern and Southern Lights—illuminate polar skies with dazzling colors. These displays are triggered when charged solar particles interact with Earth’s magnetic field. While scientists understand the broad strokes of this process, the incredible variety, intensity, and rare features—such as the mysterious phenomenon called ‘Steve’—are not fully explained. Auroral substorms and their unpredictable nature also remain subjects of ongoing research. Find out more at NOAA.