Discrete auroras on Mars
#GS1 #Important Geophysical Phenomena #Space Technology
Context: Recently, the UAE’s Hope spacecraft has captured images of glowing atmospheric lights in the Mars night sky, known as discrete auroras.
- The Hope Probe, the Arab world’s first mission to Mars, took off from Earth in July 2020, and has been orbiting the Red Planet (Mars) since February 2021. It is expected to create the first complete portrait of the planet’s atmosphere.
- An Aurora is a display of light in the sky predominantly seen in the high latitude regions (Arctic and Antarctic). It is also known as a Polar light.
- They commonly occur at high northern and southern latitudes, less frequent at mid-latitudes, and seldom seen near the equator.
- While usually a milky greenish color, auroras can also show red, blue, violet, pink, and white. These colors appear in a variety of continuously changing shapes.
- Auroras are not just something that happens on Earth. If a planet has an atmosphere and magnetic field, they probably have auroras.
What causes an aurora on Earth?
- Auroras are caused when charged particles ejected from the Sun’s surface — called the solar wind — enter the Earth’s atmosphere.
- The typical aurora is caused by collisions between charged particles from space with the oxygen and nitrogen in Earth’s upper atmosphere.
- These particles are harmful, and our planet is protected by the geomagnetic field, which preserves life by shielding us from the solar wind.
- However, at the north and south poles, some of these solar wind particles are able to continuously stream down, and interact with different gases in the atmosphere to cause a display of light in the night sky.
- This display, known as an aurora, is seen from the Earth’s high latitude regions (called the auroral oval), and is active all year round.
How are Martian auroras different?
- Unlike auroras on Earth, which are seen only near the north and south poles, discrete auroras on Mars are seen all around the planet at night time.
- Unlike Earth, which has a strong magnetic field, the Martian magnetic field has largely died out. This is because the molten iron at the interior of the planet– which produces magnetism– has cooled.
- However, the Martian crust, which hardened billions of years ago when the magnetic field still existed, retains some magnetism.
- So, in contrast with Earth, which acts like one single bar magnet, magnetism on Mars is unevenly distributed, with fields strewn across the planet and differing in direction and strength.
- These disjointed fields channel the solar wind to different parts of the Martian atmosphere, creating “discrete” auroras over the entire surface of the planet as charged particles interact with atoms and molecules in the sky– as they do on Earth.
Aurora borealis and australis:
- In the northern part of our globe, the polar lights are called aurora borealis or Northern Lights and are seen from the US (Alaska), Canada, Iceland, Greenland, Norway, Sweden and Finland.
- In the south, they are called aurora australis or southern lights, and are visible from high latitudes in Antarctica, Chile, Argentina, New Zealand and Australia.
Significance of the findings:
- Studying Martian auroras is important for scientists, for it can offer clues as to why the Red Planet lost its magnetic field and thick atmosphere– among the essential requirements for sustaining life.
- With the information gathered during the UAE’s Mars mission, scientists will have a better understanding of the climate dynamics of different layers of Mars’ atmosphere.
What is a Magnetosphere?
- It is that area of space, around a planet, that is controlled by the planet’s magnetic field.
- The shape of the Earth’s magnetosphere is the direct result of being blasted by solar wind. The solar wind compresses its sunward side to a distance of only 6 to 10 times the radius of the Earth.
- A supersonic shock wave is created sunward of Earth called the Bow Shock.
- Most of the solar wind particles are heated and slowed at the bow shock and detour around the Earth in the Magneto sheath.
- The solar wind drags out the night-side magnetosphere to possibly 1000 times Earth’s radius; its exact length is not known.
- This extension of the magnetosphere is known as the Magnetotail. The outer boundary of Earth’s confined geomagnetic field is called the Magnetopause.
- The Earth’s magnetosphere is a highly dynamic structure that responds dramatically to solar variations.