Perseverance rover photographs auroras on Mars

On Earth, the charged particles emitted by the sun create impressive light shows in the sky. But there are also auroras on our neighboring planet. The Mars rover Perseverance has observed them, according to the US space agency National Aeronautics and Space Administration (NASA).

In mid-March, a solar flare and a coronal mass ejection (CME) occurred, which hurled a large amount of high-energy particles into space. This produced auroras on various celestial bodies in the solar system – including Mars. The Perseverance rover, which is currently traveling in the Martian crater Jezero, captured them with the SuperCam and Mastcam-Z instruments.

The images were captured by a team led by Elise Knutsen from the University of Oslo. They had been on the lookout for some time, searching for sufficiently strong solar flares. “The trick was to select a good CME that would accelerate a lot of charged particles and bring them into the Martian atmosphere,” said Knutsen.

Mars polar lights in the visible spectrum

That was the case in mid-March. The team aligned the rover's cameras and was able to capture the auroras three days after the solar flare. It is the first time that auroras have been observed from the surface of another planet, the team writes in the journal Science. They are also the first on Mars in the visible spectrum of light.

Previously, these auroras had only been observed by the Mars Atmosphere and Volatile Evolution (MAVEN) probe, which explores the Martian atmosphere. However, MAVEN has only observed them in the ultraviolet (UV) range.

Auroras occur when charged particles collide with a planet's magnetic field. However, Mars does not have a magnetic field that spans the entire planet. There are only a few areas of the planet where it is still active. The auroras on Mars occur when high-energy particles hit the Martian atmosphere. These then cause the atmosphere to glow across the entire night sky, albeit weaker and more diffuse than the auroras on Earth.

Two probes confirm the observation

The lights shimmered green, in the range of 557.7 nanometers. This green glow occurs when high-energy particles from the sun excite oxygen atoms. MAVEN and the European Mars Express probe confirmed the observation of Perseverance. This also ruled out the possibility that the green glow was a nocturnal airglow caused by the excitation of gas molecules by the sun's UV radiation.

Incidentally, the auroras would not have been visible to humans, they were too faint for that. However, with better visibility conditions and an even stronger stream of particles, it is possible that they “exceed the threshold of human vision”, the team writes.

Auroras have also been detected on Jupiter, Saturn, Neptune and Uranus, as well as on some of Jupiter's moons.

(wpl)