In addition to being impressive, the auroras of the Martian skies offer important clues as to how Red Planet water escapes into the atmosphere.
This type of aurora – known as the "proton aurora" and first identified on Mars in 2016 – occurs during the day and produces ultraviolet (UV) light. Despite being visible to the naked eye, it was detected by MAVEN Imaging UltraViolet Spectrograph (IUVS).
Recently, a team of scientists studied these Martian auroras by analyzing data accumulated over several years of observations. In the new scientific article, published Recently at JGR Space Physics, scientists report that proton aurora are the most common on Mars, "with almost 100% occurrence on the daytime side of the planet in the south during the summer."
On Earth, auroras appear when solar winds hit the magnetic field of our planet. These high-energy collisions between solar particles and atmospheric gas droplets create lights in the sky.
According to Andrea Hughes, a researcher at Riddle Aeronautical University in Florida, proton auroras also start with solar winds – but in this case, charged protons collide with a cloud of hydrogen.
Then they suck the electrons off hydrogen atoms, neutralizing the protons. When these energetic neutral atoms enter the atmosphere of Mars, collisions with molecules produce ultraviolet shines – or proton auroras.
These auroras are very common in the southern Martian summer because the summer months are those in which the hydrogen cloud is perfectly positioned to interact with the solar winds and thus produce almost constant proton auroras.
Scientists have also found that the temperature rises during the Martian summer and that clouds of dust remove water vapor from the planet's surface. "This causes hydrogen to separate into hydrogen and oxygen, causing it to escape," said Hughe, quoted by Live science.
“Because of this phenomenon, we know that when we see a proton dawn, the source is not only the solar wind, but also the water that separates and gets lost in space.”