Aditya-L1 reveals secrets of the Sun: How discovery could help predict solar storms

The Sun may be millions of kilometres away, but powerful eruptions on its surface can have consequences for life on Earth. From satellite-based navigation and communication to electricity networks, several technologies people depend on can be affected when these eruptions send enormous amounts of charged particles towards our planet.India's Aditya-L1 solar mission has helped scientists uncover a previously hidden aspect of how these eruptions behave.

The discovery could help researchers better understand how solar storms travel through space and, eventually, improve predictions of when they might reach Earth.Scientists from the Indian Institute of Astrophysics (IIA), Bengaluru, found that a solar eruption observed in August 2024 did not expand uniformly like a symmetrical bubble. Instead, it expanded unevenly, developing an asymmetric shape.The finding, published in The Astrophysical Journal Letters, challenges a commonly used assumption about how these eruptions expand close to the Sun.

Researchers arrived at the conclusion by combining observations from Aditya-L1's Visible Emission Line Coronagraph (VELC), images from Nasa's Solar Dynamics Observatory and three-dimensional modelling.But why does the shape of an eruption matter? And how could understanding its movement help scientists predict solar storms that can disrupt satellites, navigation systems and power infrastructure?What are solar eruptions and why do they matter?The Sun is not a completely stable ball of hot gas.

Its magnetic field is constantly changing, creating conditions that can trigger powerful eruptions from its outer atmosphere.One such phenomenon is a coronal mass ejection (CME). It involves the release of enormous quantities of hot, magnetised plasma from the Sun's outermost atmospheric layer, known as the corona. These eruptions can travel through interplanetary space at high speeds, carrying magnetic fields and charged particles with them.When a CME is directed towards Earth, it can interact with the planet's magnetic field and trigger a geomagnetic storm.

The strength of the disturbance depends on several factors, including the speed and magnetic properties of the incoming eruption.Such storms are not merely astronomical events. They can affect technologies that modern societies increasingly depend on, particularly those operating in space or relying on satellite-based systems.Satellites can experience disruptions to their operations and, in severe cases, damage to onboard electronics.

Solar activity can also affect radio communications and interfere with the accuracy of satellite-based navigation systems such as GPS. Strong geomagnetic disturbances can induce electrical currents in power transmission networks, potentially putting transformers and other grid equipment under stress.The effects can extend to aviation, particularly high-frequency radio communications and operations on polar routes, where exposure to space-weather disturbances can be greater.Chethan Kumar, a space expert and journalist who has extensively covered the extraterrestrial field, said solar storms can affect several systems simultaneously, including electricity supplies, radio signals and satellite-based applications.“Solar storms are also known to interfere with positioning services, so your GPS can get affected.

When GPS gets affected, your air travel becomes less reliable, and it's a cascading effect,” he said.This makes the ability to monitor and forecast solar activity important for satellite operators, communication networks, aviation authorities and power-grid managers.However, predicting the behaviour of a CME after it leaves the Sun remains a complex scientific challenge. Scientists need to establish not only where an eruption is heading but also how fast it is moving and how its structure changes as it travels through space.Why are solar storms difficult to predict?One of the biggest challenges in studying CMEs is understanding their movement in three dimensions, particularly during the initial stages of an eruption.Scientists use instruments called coronagraphs to observe CMEs.

These instruments block the bright solar disc, allowing researchers to study the much fainter corona and track eruptions as they move away from the Sun.However, conventional coronagraph images primarily capture movement across the observer's field of view. In other words, they show how an eruption travels across the sky but cannot directly establish how fast the plasma is moving towards or away from the observer.This missing information is important because a CME is a three-dimensional structure, not a flat object moving across an image.Two eruptions that appear similar in conventional images could have different three-dimensional shapes and expansion patterns.

Their interactions with the surrounding solar wind could therefore differ, potentially affecting how their speeds change during propagation.Scientists have traditionally relied on observations from multiple spacecraft positioned at different locations to reconstruct the three-dimensional evolution of CMEs. While this provides valuable information, studying eruptions close to the Sun remains particularly challenging because they evolve rapidly during these early stages.This is where Aditya-L1's VELC instrument offers an additional observational capability.How Aditya-L1 uncovered the hidden dimensionVELC is one of the primary scientific instruments onboard Aditya-L1.

It was developed by the Indian Institute of Astrophysics in Bengaluru, with substantial support from Isro.Unlike instruments that only capture images, VELC also records spectra, allowing scientists to study changes in the wavelength of light emitted by the solar corona.The technique is known as Doppler spectroscopy. It is based on the principle that the wavelength of light changes depending on the movement of the source relative to the observer.For instance, when plasma moves towards an observer, the light it emits shifts towards short…