Invisible "global auroras" have been covering Mars frequently over the past few months, according to data collected by a NASA spacecraft. The rise in these planet-wide light shows, including an unprecedented "aurora hat trick" in February, is tied to solar maximum, the peak in the sun's roughly 11-year solar cycle.
Mars is no stranger to auroras. The planet is often bombarded with high-energy radiation from the sun, known as solar energetic particles (SEPs), which penetrate the red world's thin atmosphere and excite molecules of hydrogen, causing them to emit light, similar to how auroras work on Earth. However, unlike the southern and northern lights on our planet, Martian auroras — also known as proton auroras — emit ultraviolet light instead of visible light, meaning they cannot be seen with the naked eye.
