Blue aurora above Mars confirmed

The lights are created by localised magnetic fields in the planet's crust

NASA recreated the blue aurorae of Mars using a device called a Planeterella.
Credit: D. Bernard/IPAG — CNRS

Colourful aurorae do dance over the skies of Mars, it has finally been confirmed. First spotted ten years ago by ESA’s Mars Express, new research led by NASA, the Institute of Planetology and Astrophysics of Grenoble (IPAG), and Aalto University in Finland have confirmed that the blue lights seen above the planet are aurorae. It is the first time that aurorae that would be visible to the naked eye have been seen above a terrestrial planet other than Earth.

It has taken so long to confirm the sighting as it was thought for a long time that aurora would be impossible on Mars as it lacked the permanent magnetic field found on Earth. Aurorae happen when energetic particles from the Sun get caught by a planet’s magnetic field and interact with atoms in the planet’s atmosphere, emitting light. If there is no magnetic field, then there should be no aurora.

However, MAVEN found that there are still some local spots of increased magnetic field that still remain in the surface, called crustal magnetic anomalies. These were mostly confined to the planet’s southern hemisphere, meaning that the aurorae would be strongest here.

The difference in location is not the only difference with Martian aurora. Where as oxygen in our atmosphere colours the northern lights green and red, the nitrogen and carbon dioxide in Mars’s atmosphere means that they appear blue.

Scientists recreated the lights in a Planeterella, a spherical device that uses magnetic fields and charged particles to simulate the aurora. By replacing the air around the Planeterella with carbon dioxide researchers at NASA were able to recreate the blue lights that Mars Express saw above the red planet.

Currently only Mars Express has ever seen the aurora, as all the current inhabitants of the planet are robots based in the equatorial regions of the planet. But humans should be heading to the surface as soon as the 2030s. Could these explorers be the first to see blue southern lights in the skies over the Red Planet?

But the research is not simply about picking out extra-terrestrial holiday spots for future generations. The research also hopes to tell us more about other planetary atmospheres, and our own.

“Our planetary research gives us good insight on physics in the Martian atmosphere — how it evolved, why Mars’ mass is different than Earth’s,” said Guillaume Gronoff, a research scientist at NASA’s Langley Research Center who helped to lead the study. “It helps us to better understand planetary atmosphere emissions, ultimately helping us to discover habitable planets.”


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