As the Sun unleashed one of the strongest eruptions in over two decades in 2024, the results were visible not just on Earth, but across the Solar System.
The Perseverance rover watched the impact felt by the Martian skies as they turned green from the solar storm that left the Sun on March 15, 2024.
The Sun produced a solar flare and an accompanying coronal mass ejection (CME), a massive explosion of gas and magnetic energy that carried with it large amounts of solar energetic particles.
“This exciting discovery opens up new possibilities for auroral research and confirms that auroras could be visible to future astronauts on Mars’ surface.” Elise Knutsen, a postdoctoral researcher at the University of Oslo said.
Scientists had long theorised that green auroras also occur on Mars just as on Earth. Due to the Red Planet’s lack of a global magnetic field, Mars has different types of auroras than those we have on Earth.
The team determined the optimal angle for the Perseverance rover’s SuperCam spectrometer and Mastcam-Z camera to successfully observe the SEP aurora in visible light. “The trick was to pick a good CME, one that would accelerate and inject many charged particles into Mars’ atmosphere,” said Knutsen.
The coronal mass ejection that left the Sun on March 15 struck Mars a few days later providing a light show for the rover to capture, showing the aurora to be nearly uniform across the sky.
By coordinating the Perseverance observations with measurements from MAVEN’s SEP instrument, the teams could help each other determine that the observed 557.7 nm emission came from solar energetic particles.
“Perseverance’s observations of the visible-light aurora confirm a new way to study these phenomena that’s complementary to what we can observe with our Mars orbiters,” said Katie Stack Morgan, acting project scientist for Perseverance.
Researchers said that a better understanding of auroras and the conditions around Mars that lead to their formation is especially important as space agencies prepare to send human explorers there safely.