The Perseverance rover, a NASA Mars exploration vehicle, has captured a visible green aurora for the first time on the surface of Mars. This phenomenon evenly illuminated the entire Martian night sky, showcasing a stark contrast to the more localized and diverse way auroras appear on Earth.
According to a research summary published on Wednesday (May 14th) in “Science Advances”, this aurora appeared on Mars on March 18, 2024, when a strong solar flare erupted followed by a coronal mass ejection colliding with Mars. Data from the Perseverance rover revealed a green spectral line associated with excited oxygen molecules on Mars, similar to the signals emitted during auroras on Earth.
The rover also captured an image of a yellow-green sky juxtaposed against a mountainous landscape in the Jezero Crater, providing scientists with a true visual representation that allows them to witness the aurora phenomenon that was previously only imagined. This marks the first time an aurora has been captured from the surface of a planet beyond Earth.
“For two years, I have been imagining this image: a black horizon resembling ridges with a sky glowing green behind it, and that’s exactly what (the Mars rover) saw,” said Elise Wright Knutsen, the lead author of the study and a researcher at the University of Oslo. “Finally capturing it is truly gratifying.”
Previously, auroras observed on Mars only appeared in the ultraviolet spectrum, while this current aurora appeared in the visible light spectrum.
Compared to the dazzling aurora photos on Earth, Knutsen admits that this photo may not appear as vibrant, mainly due to the rover’s camera not being optimized for nighttime photography. Nonetheless, this image remains the first visible Mars aurora picture captured with the naked eye.
“Imagining that we might see it is truly fascinating,” Knutsen, a member of the Perseverance rover’s SuperCam team, said. “Furthermore, it paves the way for studying the magnetosphere, atmosphere, and space weather on Mars.”
Researchers wrote, “Although the brightness of this (aurora) event was diminished by dust, under better observation conditions or with more intense ion precipitation, the aurora’s brightness could exceed human visual threshold, which future astronauts could also see.”
Researchers also pointed out that this is the first observation of an aurora on the surface of a planet beyond Earth. Previous observations were conducted from the planet’s orbit.
“Auroras are the visible manifestation of how the sun affects a planet’s atmosphere,” Knutsen said. “It allows you to explore how particles move and inject into the atmosphere in a very direct way.”
However, the concept of Martian auroras has long puzzled scientists. Firstly, Mars does not have a global magnetic field like Earth, only a few regions with strong magnetic fields. Secondly, the Martian atmosphere is much thinner than Earth’s, with fewer molecules (such as oxygen) that can be excited.
The Perseverance rover was launched in 2020 and has been exploring the Jezero Crater on Mars since 2021, collecting dust and rock samples with the ultimate goal of returning to Earth. The region is now dried up and may have once been a flowing lake and river delta, or potentially harbored evidence of ancient microbial life.
(This article was referenced from reports by The Washington Post and the Associated Press)