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Yes, European Space Agency detected ‘green glow’ of oxygen around Mars

“Green glow detected around Mars,” claims a graphic shared on Facebook. It shows an image of a planet encircled by a bright green ring.

“ESA observed a green ring of oxygen around Mars for the first time in human history. Mars is the only planet in the universe (aside from earth) where such a phenomenon has been witnessed.”

ESA is the European Space Agency, an intergovernmental organisation of 22 member states dedicated to the exploration of space.

Facebook flagged the graphic as potentially false. We investigated. 

Mars first planet, other than Earth, where glow detected

On 15 June 2020 ESA announced that the ExoMars Trace Gas Orbiter had “detected glowing green oxygen in Mars’s atmosphere”.

ESA explained that the orbiter’s mission was to search for evidence of methane gas, which could be a sign of “active biological or geological processes on Mars”. It has been orbiting Mars since October 2016.

Unlike Earth’s oxygen-rich atmosphere, Mars’s atmosphere is mostly made up of carbon dioxide molecules, the Smithsonian magazine explains. The glow occurs as these molecules break down into carbon monoxide and oxygen. 

The ESA confirmed that this was the first time this type of green glow emission had been detected around any planet other than Earth. 

The findings were published in the journal Nature Astronomy on 15 June.

Earth’s green glow

The “green glow” on Earth is oxygen produced when “energetic electrons from interplanet

ary space hit the upper atmosphere,” the ESA said.

A video by the National Aeronautics and Space Administration, or Nasa, in the United States explains that “the green light occurs around Earth when oxygen atoms become excited through collisions with oxygen molecules”. 

“This oxygen-driven emission of light gives polar auroras” – known as the northern lights in the northern hemisphere and the southern lights in the southern hemisphere – “their beautiful and characteristic green hue,” the ESA said

CNN said the green glow had been found by researchers in all the data gathered by the orbiter. “While this agrees with the theoretical models that suggested Mars would have this glow, it's much stronger than the visible emission created by Earth.”

The graphic shared on Facebook is correct. But the significance of the green glow around Mars is still to be determined by scientists. – Taryn Willows


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