NASA’s Perseverance rover has detected an aurora on Mars for the first time in visible light.
The event occurred on March 18, 2024, when high-energy particles from the sun interacted with the Martian atmosphere, creating a subtle glow in the night sky. While satellites have captured auroras on Mars in ultraviolet light, this marks the first observation in the visible spectrum.
Just a few days prior, a solar flare and subsequent coronal mass ejection—an explosion of gas and magnetic energy—released a significant number of solar particles into space. Mars, being the fourth planet from the Sun, experienced this influx.
Scientists had anticipated this occurrence and had the rover’s instruments geared up to observe the anticipated aurora. Perseverance is equipped with two instruments that can detect visible light. The Supercam Spectrometer was used to pinpoint the wavelength of the green glow, while the Mastcam-Z captured images of the illuminated sky.
Auroras on Mars form similarly to those on Earth, where energy-rich particles collide with atmospheric atoms and molecules, leading to the emission of light from subatomic particles called electrons.
“On Earth, these charged particles are directed to the polar regions by the planet’s magnetic fields,” explained Ellis Wright Knudsen, a postdoctoral researcher at the Center for Space Sensors and Systems at the University of Oslo and lead author of a related study published recently. “Mars, lacking a significant magnetic field, allows charged particles to impact the entire planet, resulting in auroras spread across its surface,” he added.
The green hue observed was due to solar particles interacting with Martian oxygen. Although the aurora was remarkable, it was quite faint—similar to auroras seen in the most northern and southern parts of Earth.
This particular aurora wouldn’t have been visible to the naked eye, but a stronger solar storm in the future might illuminate it enough for astronauts to witness.
No impact from this event reached Earth.
All planets with an atmosphere in the solar system experience auroras.
“Previously, different types and wavelengths of auroras have been identified by orbital satellites around Mars. The earlier observations were in ultraviolet light, while this time we noted discrete arcs and patches,” the researchers pointed out.
If humans were to visit Mars and perhaps establish a long-term presence, they could enjoy a stunning light display in the Martian night sky.
“I think if we could create brighter auroras during stronger solar storms, the sight of a green sky stretching from horizon to horizon would be both eerie and beautiful,” Knudsen commented. “The aurora manifests as a gentle green glow across the sky, although dust in the lower atmosphere may blur some light nearer the horizon. Looking directly up, especially from a diagonal angle, reveals a more vibrant aurora through the thicker atmosphere,” he elaborated.
