Green glow seen in the atmosphere of Mars, similar to Earth's from space station

One of the brightest emissions on Earth is a night glow, from a wavelength of light emitted by oxygen that hasn't been seen on another planet.


Astronomers have identified a green glow in the Martian atmosphere, not unlike the glow observed by astronauts from the space station when they look towards the Earth.

According to a BBC report, the glow comes from oxygen atoms when they get excited by sunlight. While it has long been predicted to occur on other planets, the Trace Gas Orbiter (TGO), which is a joint European-Russian satellite at Mars, is the first to make the observation outside Earth.

"You’d never plan a mission to go look for this kind of thing. Today, we have to be very clear about the science we’re going to do before we get to Mars," Dr Manish Patel from UK's Open University said, speaking about the finding. "But having got there, we thought, ‘well, let’s have a look’. And it worked."

 Green glow seen in the atmosphere of Mars, similar to Earths from space station

Artist's impression of the TGO at Mars. The TGO detects the excited oxygen not with an imaging camera (hence no pretty pictures) but with its Nomad spectrometer package. This instrument sees the oxygen at very particular altitudes. Image: ESA

The study's results, published in the journal Nature Astronomy, add that the emissions are a consequence of collisions between atmospheric molecules and charged particles that are racing away from the Sun. On Earth, these interactions are heavily influenced by the planet's strong magnetic field, which pulls the particles down towards the two magnetic poles.

In a statement by the European Space Agency, lead author Jean-Claude Gerard of the Universite de Liege in Belgium said, “One of the brightest emissions seen on Earth stems from night glow. More specifically, from oxygen atoms emitting a particular wavelength of light that has never been seen around another planet.”

The statement also points out that this emission has been predicted to exist at Mars for around 40 years.

Astronauts aboard the ISS in 2011 saw a green band of oxygen glow is visible over Earth’s curve. On the surface, portions of northern Africa are visible, with evening lights shining along the Nile river and its delta. Image: NASA

Astronauts aboard the ISS in 2011 saw a green band of oxygen glow is visible over Earth’s curve. On the surface, portions of northern Africa are visible, with evening lights shining along the Nile river and its delta. Image: NASA

Jean-Claude and the team were able to spot the emission using NOMAD (Nadir and Occultation for Mars Discovery) and including the ultraviolet and visible spectrometer (UVIS).

Co-author of the study Ann Carine Vandaele, Principal Investigator of NOMAD, said that the study's authors decided to point at the ‘edge’ of Mars and found emission at an altitude of around 80 kilometres, which also depended on the changing distance between Mars and the Sun.

Understanding the properties of the Mars atmosphere is key towards operating missions to the planet, USA Today reported.

According to the ESA, studying the glow of the planetary atmospheres can provide a host of information about its composition and dynamics, even revealing how energy is deposited in it by both the sun’s light and solar wind.


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