Just in case you got so distracted with Perseverance and Zhurong's adventures on Mars and forgot the United Arab Emirates' Mars Hope orbiter is also currently there, incredible new images of the peculiar aurorae that happen on the Red Planet, captured on camera for the first time, should do the trick.
These light shows might be visible to the human eye, but the peak of their emission is found in more energetic wavelengths we can't see. Hope used its ultraviolet spectrometer to catch the events multiple times over the last few months.
Hope reached orbit around the Red Planet in February 2021. The scientific objective for the mission is to study its atmosphere and provide a deep understanding of the changes in the planet from a water-rich world to the frigid dry desert we see today. The new images of Mars's weird auroras were taken before the mission officially began. Scientists were testing the instruments when they spotted the nightside aurora that astronomers have been struggling to study for years.
There are three types of auroras that occur on Mars. One kind on the daylit side, and two on the nighttime side. One of these only occurs during solar storms, lighting up the whole side of the planet, and the other kind – the one snapped by Hope – is known as "discrete" and isn't tied to solar storms but only occurs in certain locations on the night side.
The three observations were taken on April 22, April 23, and May 6, 2021, and show highly structured discrete auroral events across the night side of Mars. What is peculiar is the location. Instead of being near the higher latitudes, like auroras on Earth, they are found at seemingly odd locations far above the surface of the Red Planet.
The reason for this is that their formation is different from our Earthly Northern and Southern Lights. Charged particles from the Sun travel across the Solar System. On Earth, they are channeled by the magnetic field towards northern latitudes where they collided with the atoms that make up our planet’s atmosphere. These interactions release light creating gorgeous effects in the nighttime.
The situation on Mars is different. With a thin atmosphere and no magnetic field, there are no spectacular polar lights. As mentioned, some of the intense auroral activity actually happens on the dayside and has been recorded by orbital observatories such as NASA’s MAVEN. The particles from the Sun smack into the Martian atmosphere and light it up.
Hope’s aurorae, while being on the nightside, also have the same underlying mechanism. But in lieu of being carried by a strong planet-wide magnetic field, charged particles from the Sun are moved about by patchy regions of magnetic rocks creating aurorae at different latitudes.
The Emirates Mars Ultraviolet Spectrometer was designed to study, among other things, these emissions. The observations not only expand our understanding of space weather effects on Mars but also about other properties of the planet.