2026 will be a year like no other for India's Sun mission

Hind Al Soulia - Riyadh - NEW DELHI — For Aditya-L1, India's first solar observation mission in space, the year 2026 is expected to be like no other.

It's the first time the observatory – which was placed in orbit last year — will be able to watch the Sun when it reaches its maximum activity cycle.

According to Nasa, it comes roughly every 11 years when the Sun's magnetic poles flip — the Earth equivalent would be the North and South poles swapping positions.

It's a time of great turbulence. It sees the Sun transition from calm to stormy and is marked by a huge increase in the number of solar storms and coronal mass ejections (CMEs) — massive bubbles of fire that blow out of the Sun's outermost layer called corona.

Made up of charged particles, a CME can weigh up to a trillion kilograms and can attain a speed of up to 3,000km (1,864 miles) per second. It can head out in any direction, including towards the Earth. At top speed, it would take a CME 15 hours to cover the 150 million km Earth-Sun distance.

"In the normal or low-activity times, the Sun launches two to three CMEs a day," says Prof R Ramesh of the Indian Institute of Astrophysics (IIA). "Next year, we expect them to be 10 or more daily."

Prof Ramesh is the principal investigator on Visible Emission Line Coronagraph, or Velc — the most important of the seven scientific instruments on Aditya-L1 — and closely monitors and decodes the data it gathers.

Studying CMEs is one of the most important scientific objectives of India's maiden solar mission, he says. One, because the ejections provide an opportunity to learn about the star at the centre of our solar system, and two, because activities that take place on the Sun threaten infrastructure on Earth and in space.

CMEs rarely pose a direct threat to human life, but they do affect life on Earth by causing geomagnetic storms that impact the weather in near space, where nearly 11,000 satellites, including 136 from India, are stationed.

"The most beautiful manifestations of a CME are auroras, which are a clear example that charged particles from Sun are travelling to Earth," Prof Ramesh explains.

"But they can also make all the electronics on a satellite malfunction, knock down power grids and affect weather and communication satellites."

The most powerful solar storm ever recorded was the Carrington Event in 1859, which knocked out telegraph lines across the globe. More recent events were recorded in 1989, when a part of Quebec's power grid was knocked out, leaving six million people without power for nine hours. In November 2015, solar activity disrupted air traffic control, leading to chaos in Sweden and some other European airports.

In February 2022, Nasa reported that a CME had led to 38 commercial satellites being lost.

Prof Ramesh says that if we are able to see what happens on the Sun's corona and spot a solar storm or a coronal mass ejection in real time, record its temperature at origin and watch its trajectory, it can work as a forewarning to switch off power grids and satellites and move them out of harm's way.

There are other solar missions watching the Sun, but Aditya-L1 has an advantage over others, including the Solar and Heliospheric Observatory sent jointly by Nasa and Esa (European Space Agency), when it comes to watching the corona.

"Aditya-L1's coronagraph is the exact size that lets it nearly mimic the Moon, fully covering the Sun's photosphere and allowing it an uninterrupted view of almost all of the corona 24 hours a day, 365 days a year, even during eclipses and occultations," says Prof Ramesh.

In other words, the coronagraph acts like an artificial Moon, blocking the Sun's bright surface to let scientists continuously observe its faint outer corona -something the real Moon does only during eclipses.

Moreover, this is the only mission that can study eruptions in visible light, letting it measure a CME's temperature and heat energy — key clues that show how strong a CME would be if it headed toward Earth, says Prof Ramesh.

To prepare for next year's peak solar activity period, the IIA collaborated with Nasa to study the data it gathered from one of the largest CMEs that Aditya-L1 has recorded until now.

It originated on 13 September 2024 at 00:30 GMT, Prof Ramesh says. Its mass was 270 million tonnes — the iceberg that sank Titanic was 1.5 million tonnes, he says.

At origin, its temperature was 1.8 million degrees Celsius and the energy content was equivalent to 2.2 million megatons of TNT – in comparison, the atomic bombs on Hiroshima and Nagasaki were 15 kilotons and 21 kilotons respectively.

Even though the numbers make it sound incredibly large, Prof Ramesh describes it as a "medium-sized" one.

The asteroid which wiped out the dinosaurs on Earth was 100 million megatons and during the Sun's maximum activity cycle, he says, we could see CMEs with energy content equal to even more than that.

"I consider the CME we evaluated to have occurred when the Sun was in the normal activity phase. Now this sets the benchmark that we'll be using to evaluate what is in store when the maximum activity cycle occurs," he says.

"The learnings from this will help us work out the countermeasures to be adopted to protect satellites in near space. They will also help us gain a better understanding of near-Earth space," he adds. — BBC