Atype of aurora on Mars -- first identified by National Aeronautics and Space Administration's (Nasa) MAVEN spacecraft in 2016 -- is the most common form of the lights occurring on the Red Planet, according to a study which can help track water loss from the Mars's atmosphere.
The study, published in the Journal of Geophysical Research - Space Physics, noted that aurora on the Earth are commonly seen as colourful displays of light in the night sky near the polar regions.
However, the researchers from Nasa's Goddard Space Flight Center (GSFC) in the US, said that the phenomenon on Mars, called a proton aurora, happens during the day and gives off ultraviolet light.
They said it is invisible to the human eye but detectable to the Imaging UltraViolet Spectrograph (IUVS) instrument on the MAVEN -- Mars Atmosphere and Volatile Evolution -- spacecraft.
The spacecraft's mission is to investigate how Mars lost much of its atmosphere and water, transforming its climate from one that might have supported life to one that is cold, dry, and inhospitable.
PROTON AURORA
According to the researchers, the proton aurora is generated indirectly by hydrogen derived from Martian water which is in the process of being lost to space.
So they said that this aurora could be used to help track ongoing Martian water loss.
"In this new study using MAVEN/IUVS data from multiple Mars years, the team has found that periods of increased atmospheric escape correspond with increases in proton aurora occurrence and intensity," Andrea Hughes of Embry-Riddle Aeronautical University in the US said.
The study noted that the proton aurora form when the sub atomic particles, protons, from solar winds interact with the upper atmosphere on the dayside of Mars.
Approaching Mars, the researchers explained that these protons transform into neutral atoms by stealing electrons from hydrogen atoms in a huge gas cloud surrounding the Red Planet.
When the high-speed incoming atoms hit the Martian atmosphere, some of their energy is emitted as ultraviolet light, the Nasa scientists said.
During southern summer on Mars, the Red Planet is near its closest distance to the Sun in its orbit and huge dust storms can occur, they added.