New Delhi

Advertisment

Every few months, a science story goes viral on the realms of internet, warning us of impending doom brought by the biggest object in our solar system. "The Sun has ejected a massive solar storm" is the usual headline, followed by a warning that it may destroy life on planet Earth as we know it. 

Usually, such headlines are alarmist in nature, designed to garner clicks but there is an element of truth to it. The surface of the Sun is extremely chaotic, roiling with immense amounts of energy, waiting to be expended. When this box of billions of kilojoules of energy is released, they are called solar storms. 

An umbrella term called 'space weather' is used to define a whole chain of phenomena and events that begins with the solar wind and solar storm. It includes their effects on Earth’s atmosphere, satellites, and ground-based systems.  

Advertisment

Solar flares and coronal mass ejections

Last week, the Indian Space Research Organisation (ISRO) shared the first images captured by its Aditya-L1 solar mission. The pictures were clicked by the Solar Ultraviolet Imaging Telescope (SUIT) instrument in wavelengths ranging from 200 to 400 nm and showed characteristic features of the Sun, including the large sunspots.

The sunspots are able to emit powerful coronal mass ejections (CMEs) that can slam into Earth and trigger potentially dangerous geomagnetic storms, regardless of whether we can see the dark patches or not. 

Advertisment

This means we can be caught off guard by extreme space weather events. The huge clouds of electrified gas travel at speeds of hundreds of miles per second and can affect power grids, communications, GPS navigation, air travel and satellites. 

Also read | Big solar flare incoming? Intriguing black patch on Sun captured by Perseverance Mars rover

How are solar flares/sunspots formed?

Solar activity follows a regular pattern with peaks and lows occurring every 11 years. These cycles, known as solar maximum and solar minimum, are driven by the Sun's magnetic field. 

We are currently in Solar Cycle 25 and expected to reach a solar maximum around July 2025. However, this cycle has shown greater activity than anticipated by NASA and the NOAA (National Oceanic and Atmospheric Administration), with the official prediction of around 115 sunspots at the peak. 

Scientists are unsure why the Sun has been more active than expected, and further observation is necessary to improve future predictions and deepen our understanding of the Sun's internal processes.

Apart from the Solar Dynamics Observatory, NASA's Perseverance Mars rover, using its Mastcam-Z camera system also captures images of the Sun daily. While the main aim is to gauge the amount of dust present in the Martian atmosphere, the camera is also able to capture the sunspots. The rover manages to spot these sunspots early because Mars is orbiting the far side of the Sun and thus has a week's headstart over Earth.

Earth-orbiting satellites have already registered three M-class flares and nearly a dozen C-class flares since first spotting the sunspot group, numbered AR3490 and its cracking flares. 

Watch | WION Fineprint: NASA announces plans for a nuclear rocket

 

Auroras and STEVE

However, in most instances, the CMEs pass over the surface of the Earth without doing much damage. The magnetic field of Earth ensures that charged solar wind is deflected to the poles, often resulting in the formation of bright celestial lights we know as auroras: aurora borealis, or the northern lights, near the North Pole; and aurora australis, the southern lights, near the South Pole.

Then there is another phenomenon in STEVE (Strong Thermal Emission Velocity Enhancement) which is a strange mauve-and-white light observed near the equator. This light show is sometimes accompanied by a striped green feature known as a picket fence.

Although scientists are uncertain about the origin of STEVE, a school of researchers believes that it is also caused by the solar storms that kiss Earth before leaving for the next planet. 

Also read | ISRO's Aditya-L1 spacecraft captures majestic pictures of sunspots

Previous large scale disruptions

It is not to say that solar storms always lead to beautiful auroras or STEVE. Between October and November 2003

During a period of intense solar activity in October and November 2003, one solar flare's magnitude was so immense that NOAA (US agency charged with forecasting weather and monitoring atmospheric conditions) had to alter its charts. 

In 1989, Quebec, the largest province by area in Canada suffered power outages for over nine hours due to a solar storm. Between September 1-2 in 1859, history's largest solar storm, known as the 'Carrington Event' was recorded. In under 18 hours, the CME travelled 150 million km to Earth and unleashed fury upon our planet. 

Usually, it takes multiple days for CME to reach Earth but such was the intensity that not only it reached within 24 hours, but also wreaked havoc with our rather primitive technology. According to reports, there were instances of sparking in numerous telegraph machines, operators receiving electric shocks and papers getting blazed by the rogue sparks. 

(With inputs from agencies)