Scientists Spot a Sun Halo on Mars Sky Via Perseverance Rover: Here’s Why this is a Big Deal

A sun halo holds a lot of information about a planet's atmosphere, thus making the Martian observation critical for space research.


Of all the bodies that have been well studied and researched, Mars, our closest planetary neighbour, is right at the top — alongside the moon. That, however, does not mean that we already know a lot about it, and there are plenty of reactions and scientific details about the Red Planet that remain missing from researchers on Earth. Addressing one such aspect, a recently published research paper has revealed the first time that Perseverance, the ground rover operated by USA’s space agency NASA, has seen a sun halo on Mars.

What is a Sun Halo, and Why is it Important?

In a research article published earlier this month, on September 3, in the Geophysical Research Letters journal, Mark Lemmon, the lead researcher of the project and planetary scientist at The Space Science Institute, Boulder in USA, explained why this is a rare occurrence, and what this says about the Martian atmosphere — and atmospheres in general.

A sun halo, as the research details, forms when the atmosphere of a planet — namely Earth — forms ice crystals of certain gasses and elements due to temperature and pressure in the region. These crystals refract the sun’s incoming light, which disperses the light rays, and therefore creates a halo around the circumference of the sun as we see it from the ground.

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The same principle applies for Mars as well, and spotting a sun halo on Mars would have helped scientists understand more properties of the Martian atmosphere and the way it reacts to gravity and other conditions. However, the Martian orbiters had so far failed to notice such properties of the Mars atmosphere — until NASA’s Perseverance rover’s navigation camera captured images of the sun from the Red Planet’s surface, which showed the sun halo.

The scientists categorically ruled out multiple factors that could have led to the presence of the halo around the sun in the image — including camera interference and dust. As a result, Lemmon says that this could be a big contributor to the way scientists on Earth study atmospheres outside of Earth.

Among many factors, understanding how the sun halo is formed could help us identify atmosphere that could be potentially life supporting — and also understand the various chemical compositions of exoplanets that we observe on a regular frequency.