Under clear skies, the brightness can be bright enough for humans to see and the rover to navigate on dark nights. Night glow is also seen on Earth. It was expected on Mars, yet had never been seen in visible light until now.

Oxygen nightglow production on Mars. Image credit: ESA

light the way

Atmospheric nightglow occurs when two oxygen atoms combine to form a single oxygen molecule, about 50 km above the planet’s surface.

Oxygen atoms are on a journey: They are formed on the Martian dayside when sunlight energizes carbon dioxide molecules, causing them to break apart. When oxygen atoms move towards night and stop being excited by the Sun, they recombine and emit light at lower altitudes.

This image shows an artist’s impression of what night lights might look like to an astronaut in the polar winter regions of Mars at night. The green glow occurs when oxygen atoms high in the atmosphere combine to form oxygen molecules. Image Credit: NASA/JPL-Caltech/Cornell University/Arizona State University- EW Knutson

“This emission is caused by the recombination of oxygen atoms created in the summer atmosphere and transported by winds to the high winter latitudes at an altitude of 40 to 60 km in the Martian atmosphere,” explains Laurean Soret, researcher. Laboratory of Atmospheric and Planetary Physics of the University of Liège in Belgium, and part of the team that published the discovery nature astronomy,

The light emitted from the night sky may be bright enough to illuminate the path to the future, seeing bright flashes like moonlit clouds on Earth.

Air glow was observed in Earth’s atmosphere from the International Space Station. Image Credit: NASA

“These observations are unexpected and interesting for future visits to the Red Planet,” says Jean-Claude Gerard, lead author of the new study and planetary scientist at the University of Liège.

follow the green flashing road

The international scientific team was surprised by this previous search Created using Mars Express, who observed the night glow in infrared wavelengths a decade earlier. Trace Gas Orbiter detected it glowing green oxygen Atom above the dayside of Mars in 2020 – the first time this daylight emission was seen around a planet other than Earth.

These atoms also travel during the night and then recombine at lower altitudes, resulting in the night lights seen in new research published today.

Artist’s image of the ExoMars Trace Gas Orbiter looking at green oxygen in daylight on Mars. Image credit: ESA

Orbiting the Red Planet at an altitude of 400 km, TGO was able to monitor the night side of Mars with its ultraviolet-visible channel. wandering machine, The instrument covers the spectral range from near ultraviolet to red light and was oriented toward the edge of the Red Planet to better observe the upper atmosphere.

The NOMAD experiment is led by the Royal Belgian Institute for Space Aeronomy, working with teams from Spain (IAA‐CSIC), Italy (INAF‐IAPS) and the United Kingdom (Open University).

The glow of the Milky Way and Earth’s air from the space station. Image credit: NASA/Scott Kelly

scientific value

Nightglow serves as a tracer of atmospheric processes. This can provide abundant information about the composition and dynamics of a region of the atmosphere that is difficult to measure, as well as oxygen density. It may also explain how energy is deposited by both sunlight and the solar wind – the stream of charged particles emitted from our star.

Understanding the properties of Mars’ atmosphere is not only scientifically interesting but also important for missions to the surface of the Red Planet. For example, atmospheric density directly affects the drag experienced by orbiting satellites and the parachutes used to deliver probes to the surface of Mars.

nightglow vs aurora

Night flashes are also seen on Earth, but should not be confused with auroras. Aurora is the way planets’ atmospheres light up.

Auroras arise, on Mars Such as on Earth, when energetic electrons from the Sun hit the upper atmosphere. They vary by location and time, while night light is more homogeneous. Both nightglow and aurora can display a wide range of colors, depending on which atmospheric gases are most abundant at different altitudes.

The green night light on our planet is quite faint, and so is best seen when viewed from an ‘edge-on’ perspective – as shown in many great images Taken by astronauts from the International Space Station.

Source: European Space Agency