Astronomers have suspected it for some time, but can now finally confirm it: at night the sky near the poles of the red planet turns green. The green glow is good news for astronauts, especially those who are afraid of the dark.
According to researchers, the green glow is so bright that astronauts – but also rovers – near the poles can effortlessly find their way on the otherwise dark planet, even at night. That can be read in Nature Astronomy.
Light in the dark
First let’s take a step back, because where does this mysterious green glow come from? The story begins on the dayside of Mars, where carbon dioxide (CO2) molecules swirling around in the atmosphere. When the sun’s light shines on these molecules, they gain so much energy that they fall apart. This process produces luminous oxygen atoms. “These oxygen atoms are then captured by the wind and transported to the dark side of the planet, where they react with each other to produce the green glow,” said Lauriane Soret, one of the scientists who worked on the study.
It is the first time that this ‘night glow’ has been observed within the visible light spectrum. This glow had previously been observed, but in infrared light; in 2020, the green glowing oxygen atoms were observed for the first time in the atmosphere using the Trace Gas Orbiter (TGO), but on the dayside of Mars. It is now known how these oxygen atoms continue their journey.
Although night glow and aurora are both natural phenomena that release (a lot of) light, there are still quite a few differences. There is also a night glow on Earth, just like on Mars. As described in this article, night glow is primarily a (chemical) process that takes place within the atmosphere of a planet. In this way, the luminous oxygen atoms form in the atmosphere and fall further away. With aurora it is really different. For example, aurora are mainly caused by solar flares and coronal mass ejections. This involves blowing away a large gas bubble imbued with magnetic field lines by the sun. Then, when a shock wave of solar wind reaches Earth’s ionosphere, a geomagnetic storm can emerge. Want to know more about geomagnetic storms? Then take a look here.
Mars landing one step closer
The discovery of night glow on Mars is of great scientific value, because it says something about the atmospheric processes taking place on the red planet. This makes it possible to conduct better research into places in the Martian atmosphere that are difficult to investigate and to see how much oxygen is present in the atmosphere. It can also say something about how exactly the light from the sun and solar winds work.
Interest
In addition, the research is of great importance if we are to ultimately land on the red planet. The lead researcher, Jean-Claude Gérard, is very happy with the results: “These observations are unexpected and interesting for future trips to Mars.” For example, the density of the atmosphere has a direct effect on how well a parachute works and how much air resistance satellites experience in the Martian atmosphere.
And finally, when people are finally ready to visit the red planet, they can also take advantage of it on the spot. Because, future astronauts take note: if you want to experience a unique light show, go to the north or south pole of Mars – and don’t forget to take your folding chair with you.
2023-11-19 12:10:04
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