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

For India’s first solar observation mission in space, Aditya-L1, the year 2026 is expected to be unlike any other.

It is the first time that the observatory – which was launched into orbit last year – will be able to see the Sun when it reaches its maximum activity cycle.

According to NASA, this occurs approximately every 11 years when the Sun’s magnetic poles reverse – Earth’s equivalent north and south poles will be swapped.

This is a time of great turmoil. 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) – huge bubbles of fire that erupt from the Sun’s outermost layer called the corona.

Composed of charged particles, a CME can weigh up to a trillion kilograms and attain speeds of up to 3,000 km (1,864 mi) per second. It can go in any direction including the Earth. At top speed, the CME will take 15 hours to cover the 150 million km Earth-Sun distance.

“In times of normal or low activity, the Sun launches two to three CMEs a day,” says Professor R Ramesh of the Indian Institute of Astrophysics (IIA). “Next year, we expect they will be 10 or more per day.”

Professor Ramesh is the Principal Investigator of the Visible Emission Line Coronagraph, or WELC – the most important of the seven scientific instruments on Aditya-L1 – and closely monitors and decodes the data it collects.

He says that studying CMEs is one of the most important scientific objectives of India’s first solar mission. One, because ejections provide an opportunity to learn about the star at the center of our solar system, and two, because the activities on the Sun threaten infrastructure on Earth and in space.

CMEs rarely pose a direct threat to human life, but they affect life on Earth by creating geomagnetic storms that affect weather in near space, where about 11,000 satellites, including 136 from India, are deployed.

“The most beautiful manifestations of CMEs are the auroras, which are a clear example of charged particles from the Sun coming towards Earth,” explains Professor Ramesh.

“But they can also cause all the electronics in the satellite to malfunction, knocking out power grids and affecting weather and communications satellites.”

The most powerful solar storm ever recorded was the Carrington event in 1859, which destroyed telegraph lines around the world. The most recent incidents were recorded in 1989, when a portion of Quebec’s power grid failed, leaving six million people without power for nine hours. In November 2015, solar activity disrupted air traffic control, causing chaos in Sweden and some other European airports.

In February 2022, NASA reported that 38 commercial satellites were lost due to a CME.

Professor Ramesh says that if we are able to observe what happens on the Sun’s corona and see a solar storm or coronal mass ejection in real time, record its temperature at the origin and watch its trajectory, it could serve as an early warning to shut down the power grid and satellites and remove them from harm’s way.

There are other solar missions tracking the Sun, but when it comes to tracking the corona, Aditya-L1 has an edge over others, including the Solar and Heliospheric Observatory jointly flown by NASA and ESA (European Space Agency).

“Aditya-L1’s coronagraph is precisely shaped to allow it to almost mimic the Moon, completely covering the Sun’s photosphere and allowing it to have an uninterrupted view of the entire corona 24 hours a day, 365 days a year, even during eclipses and occultation events,” says Professor Ramesh.

In other words, the coronagraph acts like an artificial moon, blocking out the Sun’s bright surface, allowing scientists to continuously observe its faint outer corona – something the real Moon does only during eclipses.

In addition, it is the only mission that can study outbursts in visible light, allowing it to measure the temperature and thermal energy of the CME – key clues that show how strong the CME will be if it heads towards Earth, says Professor Ramesh.

To prepare for next year’s peak solar activity period, the IIA collaborated with NASA to study data collected from one of the largest CMEs ever recorded.

It originated at 00:30 GMT on September 13, 2024, says Professor Ramesh. They say it had a mass of 270 million tons – the iceberg that sank the Titanic was 1.5 million tons.

At the time of 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.

Although the numbers make it seem incredibly large, Professor Ramesh describes it as “medium sized”.

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

He says, “I recognize that the CME we evaluated occurred when the Sun was in a normal activity phase. This now sets the benchmark that we will use to evaluate what is in store when the maximum activity cycle occurs.”

He further said, “The lessons learned will help us develop countermeasures to protect satellites in near space. They will also help us gain a better understanding of near-Earth space.”

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