How scientists detected the most powerful solar storm ever to hit Earth

Inside the global effort to track the most powerful solar storm that spawned the most powerful aurora seen in more than 500 years.


The Sun has reached peak activity in its 11-year cycle as it blasts plasma and material toward the inner and outer solar system without stopping. Earth was in the firing line when the strongest solar storm erupted from the Sun in the first week of May.

During the first full week of May, a shower of large solar flares and coronal mass ejections (CMEs) launched clouds of charged particles and magnetic fields toward Earth, producing the strongest solar storm to reach Earth in two decades.

As they collided with Earth's magnetic field, they triggered one of the strongest displays of aurora recorded in the last 500 years.


How did it all start?

Work had already begun to track peak activity on the Sun in 2023 when scientists predicted that solar maxima, periods of intense activity on the Sun, would occur earlier than anticipated. He accurately predicted this to happen in 2024.

The first signs of an impending solar storm were seen on May 7 with two intense solar flares. From May 7–11, several strong solar flares and at least seven coronal mass ejections, the most powerful explosions from the Sun, headed toward Earth. The eight flares of this period were the most powerful type, known as the X-class.

The origin was sunspot AR3664, a giant feature that is 15 times wider than Earth. Sunspots are temporary, dark areas on the Sun's surface that have a temperature of about 3,800 to 4,500 degrees Celsius. These are areas of intense magnetic activity, thousands of times stronger than Earth's magnetic field.


This giant sunspot is so huge that it can be seen with the naked eye through ordinary eclipse glasses, without the need for magnification. In the days that followed, it began to explode with the most intense flares and coronal mass ejections.

Scientists on alert

Scientists at the Center of Excellence in Space Sciences India (CESSI) were observing the increasing activity of the Sun. Their calculations showed that the mega sunspot had four times more magnetic flux, electric current and energy than the active region that produces the normal glow.

“We immediately realized that we were dealing with a highly active region capable of producing multiple strong flares and CMEs,” Dr Dibyendu Nandi of CESSI told

CESI immediately issued a rare severe category space weather bulletin and alerted scientists at ISRO and other institutions associated with India's first solar probe, the Aditya L1 mission, to begin tracking and ensuring the safety of assets in space.


Meanwhile, the Space Weather Prediction Center of the US-based National Oceanic and Atmospheric Administration (NOAA) also issued predictions and global alerts. It sent notifications to operators of power grids and commercial satellites to help mitigate potential impacts.

As the alerts began coming in, several major missions, including NASA's ICESat-2 – which studies polar ice sheets – went into safe mode. SpaceX launched countermeasures to protect Starlink satellites, which were suffering from pressure from the solar storm. ISRO's Master Control Facility (MCF) has swung into action to save more than 50 spacecraft present in India's orbit.


How bad was it?

Traveling at a speed of 48 lakh kilometers per hour, the coronal mass ejection hurtled through space to Earth. Starting on May 10, intense activity triggered stunning displays of aurora over many parts of the world, including India, one of the rarest such phenomena.

Elizabeth MacDonald, NASA's heliophysics citizen science lead, said all the CMEs arrived largely at once, and conditions were perfect to produce historic storms.

Scientists compared it to one of the largest solar events in decades and the aurora display was the best in five centuries.


What will happen next?

NASA has said that the huge sunspot that caused the storm is now on the other side of the Sun and the Earth is safe from any impact. However, it is not over yet.

Sunspot has become visible on Mars.



Photos: AFP, NASA, Getty, IISER, IIA

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