NASA rover observes aurora on Mars in visible light

16/5/2025 6:13

NASA's Perseverance rover

has observed an aurora on Mars in visible light for the first

time, with the sky glowing softly in green in the first viewing

of an aurora from any planetary surface other than Earth.



Scientists said the aurora occurred on March 18, 2024, when

super-energetic particles from the sun encountered the Martian

atmosphere, precipitating a reaction that created a faint glow

across the entire night sky. Auroras have been observed

previously on Mars by satellites from orbit in ultraviolet

wavelengths, but not in visible light.



The sun three days earlier had unleashed a solar flare and

an accompanying coronal mass ejection - a huge explosion of gas

and magnetic energy that brings with it large amounts of solar

energetic particles - that traveled outward through the solar

system. Mars is the fourth planet from the sun, following

Mercury, Venus and Earth.



Scientists had simulated the event in advance and prepared

instruments on the rover to be ready to observe the expected

aurora. Perseverance has two instruments that are sensitive to

wavelengths in the visible range, meaning they detect colors

human eyes can see. The researchers used the rover's SuperCam

spectrometer instrument to identify exactly the wavelength of

the green glow and then used its Mastcam-Z camera to take a

snapshot of the softly glowing green sky.



An aurora forms on Mars the same way as on Earth, with

energetic charged particles colliding with atoms and molecules

in the atmosphere, exciting them, and causing subatomic

particles called electrons to emit light particles called

photons.



"But on Earth, the charged particles are channeled into the

polar regions by our planet's global magnetic field," said Elise

Wright Knutsen, a postdoctoral researcher at the University of

Oslo's Center for Space Sensors and Systems and lead author of

the study published this week in the journal Science Advances.



"Mars has no global magnetic field so the charged particles

bombarded all of Mars at the same time, which leads to this

planet-wide aurora," Knutsen added.



The green color occurred because of the interaction between

the charged particles from the sun and oxygen in the Martian

atmosphere. While auroras can be brilliant, as often seen in

Earth's northernmost and southernmost regions, the one observed

on Mars was quite faint.



"This specific aurora we observed on March 18th of last year

would have been too faint for humans to see directly. But if we

get a more intense solar storm, it could become bright enough

for future astronauts to see. And with a camera, such as an

iPhone, you would clearly see it, rather like how an aurora on

Earth is always brighter in images than with the naked eye,"

Knutsen said.



This particular event did not impact Earth.



All the planets with atmospheres in our solar system

experience auroras.



"Various types and wavelengths of aurora have been observed

previously from Mars-orbiting satellites. All previous

observations have been in the UV, but they have had wildly

different shapes. From the global, diffuse aurora we observed

now, to discrete arcs and patches near the crustal fields

(regional magnetic fields) in the south, and large-scale sinuous

shapes," Knutsen said.



If astronauts from Earth visit Mars and perhaps establish a

long-term presence on the planet's surface, they may be treated

to a nighttime light show.



"During a more intense solar storm, producing a brighter

aurora, I think a sky which glows green from horizon to horizon

will be eerily beautiful," Knutsen said.



"The aurora will appear as a soft green glow covering more

or less the whole sky," Knutsen added. "Dust in the lower part

of the atmosphere would obscure some of the light towards the

horizon, and if you looked straight up it would also be fainter

simply because looking at a slant angle will allow you to see

through a thicker section of the atmosphere that is emitting the

aurora."