Tracking solar winds to spy the Sun? NASA’s PUNCH Space Mission head explains

On May 31 this year, “riotous torrents of blobs and streams” that were ejected out of the sun’s atmosphere blasted outwards at over a million miles an hour and, within a day, swept over the Earth.

This was the first solar wind that was tracked by NASA’s PUNCH Mission, a constellation of four ‘travel bag’-sized small satellites launched in the low Earth orbit (LEO) on March 11, 2025, to spy on the corona, the sun’s atmosphere, and stalk the solar winds that stretch out from it to the limits of the solar system.

“The sun ejected enormous clouded materials, they crossed the solar system and impacted the earth. And this was the first such cloud that we could track all the way from the vantage point of the Earth,” said PUNCH’s principal investigator, Craig DeForest during a public lecture on the NASA PUNCH Space Mission in Thiruvananthapuram on October 15.

The lecture was jointly organised by Indian Institute of Space Science and Technology (IIST), Breakthrough Science Society and Christ University.

“When that happened, we saw a strong aurora in Colorado the next day,” he said. Aurora is a spectacularly wild display of colourful lights upon the sky when the Sun’s charged particles clash with the Earth’s atmosphere.

Like hurricanes, the solar storm DeForest’s team witnessed erupted without warning. “Before that (the witnessing of the celestial event) we had been checking out the instruments, making sure that they could take a picture, had the right exposure time… basically checking out that the spacecraft machinery was healthy. And right at the end of May, we switched on to the science programme and started taking regular data. And the very next day a CME (coronal mass ejection) streaked across the solar system,” the renowned astrophysicist said about the first unforeseen sighting.

DeForest is also the director of the Department of Solar and Heliospheric Physics, Southwest Research Institute, Boulder, Colorado, USA. It is not just mesmerising sky lights that coronal mass ejections (CME) or solar winds produce.

“Space weather storms can affect spacecraft, aircraft, and radio communications like your cell phone. It can affect power grids. This has happened in Canada and the US, where space weather effects have either damaged or taken down power grids and caused blackouts. These winds will interfere with our satellites and trigger power outages,” DeForest said. “Things that are happening in the atmosphere of a star is actually affecting us,” he said.

PUNCH is short for ‘Polarimeter to Unify the Corona and Heliosphere’ and the data it collects is expected to provide scientists better insights on how these solar events that are potentially damaging to the Earth originate and advance.

Nonetheless, it is still too early to predict when a solar wind would erupt or, once it breaks out, the time it would take to reach the Earth. If the storm in May took just a day to accelerate from start to 149.15 million km (Sun-Earth distance), there were others that took four or five days.

“We have sophisticated models to predict the time it takes for the solar wind to reach the Earth. But it is still not possible to do it with full reliability because we haven’t had the information required,” DeForest said.

In the images captured by PUNCH, the kindergarten image of the Sun as a bright yellow ball with rays around it gets a radical overhaul. The images showed the Sun as a smouldering round mass dark-brown on the outside and burning golden-yellow on the inside, like a bonfire of thick dark logs enclosing a flaming core. “It is still not clear why the core of the Sun is hotter than its surface. It is an object of study,” DeForest said.

The corona, which the child imagines as a series of porcupine rays on the yellow circle, is like ever-forming petals that seem to elongate to infinity. “In 30 minutes things that are half the size of India are rising up and spreading out on the surface of the sun and sinking down below. This is happening all the time, everyday, round the clock, all over the star. There is a million of those on the star,” DeForest said.

And the ‘petal formations’ around the Sun kick up a mighty racket. “It is extraordinarily loud. If this sound can somehow travel through space, it would be equivalent to the sound of a freight train going by or a rock concert. That’s how violent it is,” DeForest said.

The Sun, the bright yellow round in the middle, is 14 lakh km across. But seen along with the ever-expanding corona in the PUNCH images, it seems just like a dot in the middle of an old round gramaphone record. “The corona is many times larger than the star, and it doesn’t end. It just extends outwards. It is not a smooth atmosphere like ours or a steady stream. It is full of turbulence and gusts moving outwards,” DeForest said.

The astrophysicist said that as the corona extends away from the Sun, it breaks into turbulence. He used the analogy of a water hose to describe this outward surge of the corona. “When water is shot out of a hose, the stream stays together for a while and then breaks apart. The same mathematical equation that governs the hose is governing this material as it leaves the Sun. It streams across the solar system and after a point breaks apart into droplets and gusts,” he said.

But these are relatively quite days on the heliosphere (the entire area of the solar system where the solar winds spread). A particularly boisterous day is when coronal mass ejections or large bundles of cosmic materials streak across the solar system. “These are pieces of the star’s atmosphere that have become unstable and gets ejected into space at over a million miles an hour,” he said.

It is this temperamental space weather, which can adversely affect the Earth, that PUNCH is attempting to understand.

PUNCH Mission is similar to ISRO’s solar mission Aditya L1, which also attempts to study cosmic hurricanes like coronal mass ejections. Adithya L1, however, has one large spacecraft that is placed on the L orbit, which is about 1.5 million km from the Earth.

PUNCH Mission, on the contrary, has four spacecrafts and are placed far below in the low Earth orbit, just 160 to 2000 km above Earth.