Watching an aurora flicker and glow is one of the few ways that people can directly appreciate the complex interactions between Earth’s atmosphere and the space environment that surrounds it. A particularly spectacular display occurred on 10–13 May, after an extreme solar outburst triggered the largest geomagnetic storm in decades. People at unusually low latitudes in both the Northern and Southern Hemispheres were treated to colorful auroras dancing in the night sky.
Earth was not the only planet whose skies glowed from the solar surge. Days later, the same region of the Sun erupted in the direction of Mars, which on 20 May proceeded to have its own exhibition of intense auroras. It was among the most intense auroral displays that astronomers have been able to observe on the red planet—but it was far from the first.
Space missions over the past two decades have revealed Mars to have its...
