The recent capture of images of glowing atmospheric lights in the Mars night sky, known as discrete auroras, by UAE’s Hope spacecraft has made headlines worldwide. The Hope Probe, representing the first mission to Mars by the Arab world, began its journey from Earth in July 2020 and has been orbiting Mars since February 2021. It is expected to present the first comprehensive portrait of the Martian atmosphere.
Understanding Auroras
Auroras are displays of light seen primarily in high latitude regions like the Arctic and Antarctic, hence they’re often referred to as polar lights. Even though they occur most frequently at high northern and southern latitudes, these lights can also be spotted less frequently at middle latitudes and rarely near the equator. While their common hue is a milky green, auroras can manifest in a spectrum of colors including red, blue, violet, pink, and white. Interestingly, the occurrence of auroras isn’t exclusive to Earth. Any planet endowed with an atmosphere and magnetic field is likely to have auroras.
The Cause of Auroras on Earth
Auroras are caused by charged particles from the Sun’s surface, also known as solar wind, entering the Earth’s atmosphere. These particles collide with oxygen and nitrogen in the Earth’s upper atmosphere, causing them to become ‘excited’. As a significant number of electrons transfer their energy to these atoms and molecules, they emit light detectable by the human eye, resulting in beautiful auroral displays. The lights are called aurora borealis or the Northern Lights in the north and are visible in places such as the US (Alaska), Canada, Iceland, Greenland, Norway, Sweden, and Finland. In the south, they are identified as aurora australis or the southern lights and can be seen from high latitudes in Antarctica, Chile, Argentina, New Zealand, and Australia.
Discrete Auroras of Mars
Unlike Earth, where auroras are restricted to the poles, Mars’ discrete auroras (DAs) can be seen all over the planet during nighttime. These DAs mark the areas where energetic particles excited by the atmosphere are drawn down by an inconsistent network of crustal magnetic fields originating from Martian surface minerals.
Martian Auroras are Different
Mars has a characteristically different magnetic field from Earth. Its magnetic field has mostly disappeared because the molten iron responsible for producing magnetism in its core has cooled. The Martian crust, however, which solidified billions of years ago when the magnetic field was still active, maintains some residual magnetism. Unlike Earth, which behaves like a singular bar magnet, Mars’ magnetic fields are unevenly distributed, differing in direction and strength across the planet. These disjointed fields steer the solar wind to varying parts of the Martian atmosphere, forming ‘discrete’ auroras scattered over the planet’s surface as charged particles interact with atoms and molecules in the sky, similar to Earth’s auroras.
Significance of the Study
Studying Martian auroras could provide scientists with valuable insights into why Mars lost its magnetic field and dense atmosphere, key conditions for sustaining life. The data collected during UAE’s Mars mission will further our understanding of the climate dynamics of Mars’ atmospheric layers.
Other Mars Missions
NASA’s Mars 2020 Mission (Perseverance Rover) aims to understand Mars’ geology better and seek signs of ancient life. China’s Mars Mission Tianwen-1, launched in 2019, is set to explore the planet’s soil, geological structure, environment, atmosphere, and water. Meanwhile, India’s Mars Orbiter Mission (MOM), or Mangalyaan, set off from the Satish Dhawan Space Centre in Andhra Pradesh by the Indian Space Research Organisation in November 2013.
