US, WASHINGTON (ORDO NEWS) — High in the atmosphere of Mars, astronomers discovered a phenomenon that they had hunted for decades: a faint green glow caused by the interaction of sunlight and oxygen in the upper atmosphere.
Previously, this glow was found only in one place: the sky above the Earth. Its discovery in the Martian atmosphere will help us better understand the processes that lead to airborne glow, both on Earth and on other planets.
“One of the brightest radiations observed on Earth comes from the night glow. In particular, from oxygen atoms emitting a specific wavelength of light, ”said astronomer Jean-Claude Gerard of the University of Liege in Belgium, the lead author of a new article describing this phenomenon.
“Nevertheless, according to forecasts, this emission will exist on Mars for about 40 years – and thanks to [ExoMars Trace Gas Orbiter] we found it.”
The sky of the Earth is never completely dark, even at night, even if you have extracted light pollution, starlight and diffused sunlight. Molecules in the atmosphere are constantly subjected to various processes that cause them to glow weakly in different wavelength ranges.
The glow does not differ from the radiance, since it is generated by the same particles, except that it is much weaker, and the mechanisms underlying it are different. Radiance is created by charged particles of the solar wind, which ionize the atmospheric atoms, causing them to form dancing lights in the sky.
Air luminescence is caused by the interaction of sunlight and the atmosphere and is generally divided into two categories. Nocturnal glow occurs when atoms recombine, releasing their excess energy in the form of photons. Night glow was previously observed both on Venus and on Mars, as well as on Earth.
What astronomers are now observing in the atmosphere of Mars is daylight – a phenomenon that is much more difficult to detect, given that its faint presence is significantly eclipsed in daylight.
On the Red Planet, such a glow was predicted in 1979, but probes that directly study the surface of Mars have still not been able to detect it.
So, taking the ISS experiment as a basis, the team reoriented the Nadir and Occultation for MArs Discovery (NOMAD) tool from its position, looking directly at Mars, to view through the atmosphere towards the Martian horizon. From this position, they made a series of observations of the Martian atmosphere at an altitude of 20 to 400 kilometers.
When they analyzed the data, they discovered green radiation, both at the optical and ultraviolet wavelengths.
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