Predicting the Green Glow of Aurorae on the Red Planet

Joint Meeting of the Europlanet Science Congress and the American Astronomical Society’s Division for Planetary Science (EPSC-DPS2025) Press Release

EMBARGOED FOR 08:00 EEST (05:00 UTC) ON WEDNESDAY, 10 SEPTEMBER 2025

Planetary scientists believe they can now predict the green glow of an aurora in the night sky above Mars, and they have the images to prove it.

The first observations of a visible-light aurora from the surface of the Red Planet were made by NASA’s Perseverance Mars rover in 2024. Now, presenting at the Europlanet Science Congress–Division of Planetary Science (EPSC–DPS) joint meeting in Helsinki this week, Dr Elise Wright Knutsen of the University of Oslo will reveal a second snapshot of the aurora by Perseverance and, more importantly, the tools to predict when an aurora will occur on Mars.

‘The fact that we captured the aurora again demonstrates that our method for predicting aurorae on Mars and capturing them works,’ said Knutsen, who was also the science lead for the first image of a martian aurora seen from the ground.

Aurorae are produced when a burst of energetic particles in the solar wind, belched out by a coronal mass ejection (CME) from the Sun, collide with molecules in the atmosphere, causing them to glow. Mars’s aurorae glow green as a result of the charged particles colliding with oxygen atoms high above the Red Planet, and could be bright enough that astronauts on Mars would be able to see them with the naked eye. Furthermore, because Mars does not have a magnetic field to direct the charged particles to the magnetic poles, which is where we generally see aurorae on Earth, the martian aurorae are seen all across the night-side of the planet at the same as a glow in the sky. This is called ‘diffuse’ aurora.

The same radiation that causes the aurora could also potentially be dangerous to astronauts without warning that they must take shelter, so having some idea of when a powerful solar storm will hit Mars is crucial if humans are going to one day survive on the surface.

Nonetheless, predicting aurorae on Mars is a complex business. Observations have to be planned and uploaded to the rover three days ahead once a CME bursts out in the direction of Mars. This means a lot of guesswork as to which solar storms will produce an aurora.

Knutsen’s team made eight attempts to view the aurora with Perseverance’s SuperCam and MastCam cameras between 2023 and 2024, and they found it to be a process of trial and error. The first three attempts saw nothing, but by retrospectively analysing conditions as measured by NASA’s MAVEN and the ESA’s Mars Express orbiters, Knutsen and her colleagues realised that the velocities of those CMEs had likely not been fast enough to create a solar wind disturbance at Mars.

‘The faster the CME, the more likely it is to accelerate particles towards Mars that create aurorae, and the stronger the solar wind disturbance around Mars, the more likely it is that those particles make it into Mars’s nightside atmosphere,’ said Knutsen. ‘Later, we progressively targeted faster, more intense CMEs, and that’s when we found our first two detections.’

The final three CMEs also didn’t produce aurorae, even though they met the criteria that Knutsen was looking for.

‘The last three non-detections are more curious,’ she said. ‘Statistically there is also a degree of randomness to these things, so sometimes we’re just unlucky. This perhaps isn’t that surprising, since predicting the aurora on Earth down to minute precision isn’t an exact science either.’

Aurorae on Mars have previously been observed from orbit in ultraviolet light by ESA’s Mars Express and NASA’s MAVEN missions. Now, with the addition of visible-light detections, there is a growing dataset of observations for improving the accuracy of the aurora predictions. With further observations to come, they will hopefully help solve some ongoing mysteries about how the auroral lights are triggered on Mars.

‘There is still much we don’t understand about how aurora occur on Mars as, unlike Earth, there is no global magnetic field to guide energetic solar particles onto the nightside where the aurora can be seen,’ said Knutsen. ‘Comparing the timing of solar wind disturbances, the arrival of solar energetic particles and the intensity and timing of aurora will advance our knowledge in this area.’

Further information

EPSC–DPS2025-1314 Green-Line Aurora Detection Attempts From the Surface of Mars

Elise Wright Knutsen, Timothy H. McConnochie, Mark Lemmon, Shayla Viet, Agnes Cousin, Roger C. Wiens, and James F. Bell, https://doi.org/10.5194/epsc-dps2025-1314

This research was funded by the Research Council of Norway, and the NASA Mars 2020 Program.

Images

Mars_aurora_Perseverance.tiff

An artist’s impression of how the aurora might appear in the sky above the Perseverance rover. Image credit: Alex McDougall-Page, University of Strathclyde/AstrollCareers.

https://www.europlanet.org/wp-content/uploads/2025/09/Mars_aurora_Perseverance.tiff

SCAM_ZCAM.tiff

Four images from Perseverance’s Mastcam-Z. The left hand-side images show both detections of the aurora, on 18 March and 18 May 2024. On the right are non-detections with comparable sky illumination (from Mars’s moons) to show the contrast in colours between a night with aurora and a night with no aurora. The March event was about twice as intense as the May event. The sky was also much dustier in May, which led to fewer stars being visible. The sky is generally much brighter and warmer in color in March due to Phobos, Mars’s largest moon, being in the sky. The coloured boxes show (from top to bottom): the theoretical aurora color for these images, the average sky colour, and the bottom boxes show the sky colour with the aurora signal removed or added, for left and right column respectively. This is to show what the colour of the sky would have been, theoretically, with no aurora that night, or with aurora for the comparison images. If all conditions were identical, then the two bottom boxes should diagonally have the same color, which worked close to perfectly for the May event. Below the images is the spectra from the rover’s SuperCam that identifies the green glow as the 557.7nm atomic oxygen auroral emission, indicated by the vertical green line. The solid lines are the real measurements for the two detections, while the dashed lines show our aurora model, demonstrating that the calculations estimating the aurora’s brightness from the surface with the measured dust amount corresponds very well with the observed aurora intensity. Image credit: Elise Wright Knutsen et al.

https://www.europlanet.org/wp-content/uploads/2025/09/SCAM_ZCAM.tiff

Note: A print-resolution version of the Perseverance images can be downloaded from iCloud at https://tinyurl.com/cfv4vntt until 3rd October 2025. After this date please contact the EPSC-DPS2025 Press Office or Elise Wright Knutsen for the high-res version.

Contacts

Elise Wright Knutsen

University of Oslo

elisewkn@uio.no

EPSC-DPS2025 Press Office

press@europlanet.org

Notes for Editors

About the Joint Meeting of the Europlanet Science Congress and the Division of Planetary Sciences (EPSC-DPS)

The Europlanet Science Congress (EPSC), established in 2006 as the European Planetary Science Congress, is the largest planetary science meeting in Europe. It covers the entire range of planetary sciences, with an extensive mix of talks, workshops and poster sessions, as well as providing a unique space for networking and exchanges of experiences.

EPSC joined forces for the first time with the American Astronomical Society’s Division for Planetary Sciences (DPS) for a joint meeting in Nantes, France, in 2011. This was followed by DPS-EPSC 2016 in Pasadena, EPSC-DPS 2019 in Geneva, and the return to the United States for the DPS-EPSC 2023 meeting in San Antonio. This year will mark the third iteration of a joint European-based meeting. The intent of the joint meetings is not only to connect the European and North American planetary science communities, but also to consolidate two major meetings and motivate planetary scientists from all over the globe to attend.

Follow on social media (Bluesky, X and LinkedIn) with the hashtag #EPSC-DPS2025 for updates on the meeting.

About Europlanet

Europlanet (europlanet.org) is a non-profit association and membership organisation that provides the planetary science community with access to research infrastructure, services and training. The Europlanet Association Sans But Lucratif (AISBL), established in 2023, builds on the heritage of a series of projects funded by the European Commission between 2005 and 2024 (Grant Numbers 871149, 654208, 228319 and RICA-CT-2004-001637) to support the planetary science community in Europe and around the world.

About the DPS

The Division for Planetary Sciences (DPS), founded in 1968, is the largest special-interest Division of the American Astronomical Society (AAS). Members of the DPS study the bodies of our own solar system, from planets and moons to comets and asteroids, and all other solar-system objects and processes. With the discovery that planets exist around other stars, the DPS has expanded its scope to include the study of extrasolar planetary systems as well. The American Astronomical Society (AAS), established in 1899, is the major organization of professional astronomers in North America. The mission of the AAS is to enhance and share humanity’s scientific understanding of the universe as a diverse and inclusive astronomical community, which it achieves through publishing, meeting organization, science advocacy, education and outreach, and training and professional development.