Aditya-L1 Detects Early Warning Signs Hours Before Major Solar Flares

India’s Aditya-L1 solar observatory has identified small, short-lived brightenings in the Sun’s atmosphere that appear hours before major solar flares, offering scientists a potentially important new clue in the effort to understand and eventually forecast powerful eruptions from the Sun.

The finding was announced by the Indian Space Research Organisation on 28 August 2026 and is based on simultaneous ultraviolet and X-ray observations from three instruments aboard Aditya-L1. Researchers found that these small pre-flare events tend to cluster around the same region where a much larger solar flare subsequently erupts.

The research has been published in the Monthly Notices of the Royal Astronomical Society, one of the world’s leading peer-reviewed astronomy journals, under the title Multiwavelength Diagnostics of Pre-Flare Evolution with Aditya-L1: From the Solar Chromosphere to the Corona. The study was published online on 27 July 2026 and appears in Volume 551 of the journal.

The discovery does not yet constitute an operational solar-flare warning system. It does, however, identify measurable activity that occurs before major eruptions and therefore provides an important scientific foundation for developing more reliable flare-forecasting techniques.

Small Events Appearing Before Major Solar Flares

Solar flares are sudden releases of enormous amounts of magnetic energy stored in the Sun’s atmosphere. They can produce intense bursts of electromagnetic radiation extending from radio wavelengths through ultraviolet light and X-rays.

The new Aditya-L1 research concentrated on what happens in an active region of the Sun before such a major eruption begins.

Scientists examining observations from several major flares discovered numerous brief brightenings in the lower solar atmosphere during the pre-flare period. These transient events occurred before the principal flare and were concentrated close to the location from which the much larger eruption subsequently developed.

The pattern suggests that a solar active region does not necessarily move directly from a relatively quiet state into a major flare. Instead, repeated smaller episodes of magnetic-energy release may occur beforehand as the magnetic configuration becomes progressively more unstable.

This provides scientists with a potentially valuable observational window into the physical processes taking place before a major solar eruption.

Researchers Analysed Seven Powerful Solar Flares

The underlying study examined seven M-class and X-class solar flares, among the more energetic categories of flare activity.

Using observations from Aditya-L1’s Solar Ultraviolet Imaging Telescope, researchers identified a total of 102 pre-flare transient events within the regions being examined before the major flares occurred.

These transient brightenings were detected primarily through observations of the Mg II h spectral line at approximately 2803 angstroms, which allows scientists to investigate activity in the Sun’s chromosphere.

The fact that the brightenings appeared in the Mg II channels but not in nearby continuum observations helped researchers establish that the events originated within the chromosphere rather than being simple variations elsewhere in the observational data.

The chromosphere is a comparatively thin but highly dynamic region of the solar atmosphere located above the visible photosphere and below the much hotter corona. It plays an important role in transporting and releasing energy during solar eruptions.

Many Events Occurred Near Critical Magnetic Boundaries

One of the most important results involved the location of the transient brightenings.

Researchers found that many of the events occurred close to polarity inversion lines, regions where magnetic fields of opposite polarity meet within a solar active region. These locations are particularly important in solar-flare physics because strongly sheared and complex magnetic fields can store large quantities of energy there.

The pre-flare transients were also frequently located close to the region from which the eventual major flare erupted.

This spatial relationship strengthens the argument that the brightenings are connected to the processes destabilising the active region rather than being unrelated solar activity occurring elsewhere.

Repeated small releases of energy around these magnetically complex regions may gradually alter the magnetic environment until conditions become favourable for a much larger and more explosive energy release.

Aditya-L1 Observed the Events in Ultraviolet and X-Rays

The discovery was possible because Aditya-L1 carries multiple instruments capable of observing different layers and energy regimes of the Sun simultaneously.

Three payloads played central roles in the study: the Solar Ultraviolet Imaging Telescope (SUIT), the Solar Low Energy X-ray Spectrometer (SoLEXS) and the High Energy L1 Orbiting X-ray Spectrometer (HEL1OS).

SUIT observes the Sun through eleven near-ultraviolet filters and can examine different layers extending from the upper photosphere into the chromosphere. Much of this ultraviolet radiation cannot be observed effectively from the Earth’s surface because the atmosphere absorbs it, making space-based measurements particularly valuable.

SoLEXS and HEL1OS, meanwhile, monitor solar X-ray emission associated with energetic processes occurring higher in the solar atmosphere and corona.

Combining these observations allowed scientists to connect activity occurring within the chromosphere with higher-energy processes taking place above it.

Around 28% Showed High-Energy X-Ray Counterparts

The study found that approximately 28% of the detected pre-flare transients had corresponding signatures in HEL1OS observations between 10 and 30 keV.

This is significant because X-ray emission at these energies provides evidence that at least some of the apparently small brightenings involve genuine energetic processes rather than purely passive changes in solar brightness.

Detailed analysis also revealed non-thermal X-ray emission in a subset of the events, indicating the presence of accelerated particles and suggesting that some of the transients behaved like very small flare-like energy releases.

The observations therefore support a picture in which a major flare may be preceded by a succession of smaller magnetic-energy-release events taking place within the same unstable active region.

Evidence of a ‘Hot Onset’ Before Some Flares

Researchers also identified what they describe as a hot X-ray onset in four of the seven flare events examined.

A hot onset refers to the appearance of elevated-temperature plasma before the more obvious impulsive phase of the flare develops. Detecting such activity provides another potential indication that the solar atmosphere is already undergoing important physical changes before the main eruption begins.

For the remaining three flare events, the available signal was not sufficiently strong relative to the background to determine conclusively whether a similar hot-onset phase occurred.

The researchers therefore did not assume that every major flare follows precisely the same sequence. Instead, the findings indicate a collection of observable pre-flare phenomena that can now be investigated across a much larger sample of solar events.

A Possible Path Towards Solar-Flare Forecasting

Forecasting solar flares remains one of the major challenges of space-weather science.

Scientists can identify active regions with complicated magnetic fields and estimate that some have a greater probability of producing major eruptions. Predicting precisely when and where a large flare will occur, however, remains extremely difficult.

The Aditya-L1 findings are important because the transient brightenings appear during the period leading up to an eruption and are spatially concentrated around the eventual flare location.

This raises the possibility that sufficiently systematic monitoring of such activity could eventually contribute to warning models that identify when an active region is approaching a critical state.

ISRO has described the work as a step towards more reliable flare forecasting rather than presenting the transient events as an already operational prediction method.

Further observations will be required to determine how consistently these signatures occur before major flares, whether similar activity can occur without producing a major eruption and how the different ultraviolet and X-ray signals can be combined into quantitative forecasting tools.

Why Solar Flares Matter to Modern Technology

Improving solar-flare forecasting has practical importance far beyond solar physics.

Large flares can produce intense ultraviolet and X-ray radiation capable of altering conditions in the Earth’s upper atmosphere. They can disrupt high-frequency radio communication, affect satellite navigation and interfere with some spacecraft systems.

Solar eruptions can also be associated with broader space-weather disturbances capable of affecting satellite operations and increasing radiation exposure for spacecraft and astronauts.

Modern economies increasingly depend upon satellite-based navigation, communications, Earth observation, weather forecasting and financial timing infrastructure. Understanding rapidly developing activity on the Sun therefore has direct relevance to technological resilience on Earth.

The importance of accurate space-weather forecasts will increase further as human activity expands beyond Low Earth Orbit and towards long-duration missions around the Moon and eventually deeper into the Solar System.

Continuous Observation from the L1 Point Gives Aditya-L1 an Advantage

Aditya-L1 occupies a special observing position near the Sun-Earth Lagrange Point 1, approximately 1.5 million kilometres from Earth in the direction of the Sun.

Operating around L1 allows the spacecraft to maintain an essentially continuous view of the Sun without the regular eclipses that affect many satellites orbiting close to Earth.

This persistent observational capability is particularly valuable for studying the build-up to solar flares because important precursors may occur hours before the principal eruption.

A spacecraft capable of watching the Sun continuously across several wavelengths can follow the evolution of an active region rather than observing only isolated stages of the process.

Aditya-L1 combines this uninterrupted vantage point with seven scientific payloads designed to examine the solar photosphere, chromosphere, corona, solar wind and energetic processes occurring around the Sun.

SUIT Provides a New View of the Solar Chromosphere

The Solar Ultraviolet Imaging Telescope has played an especially important role in the latest result.

SUIT observes the Sun using eleven near-ultraviolet filters, enabling scientists to examine solar features formed at different heights in the atmosphere. The Mg II h observations used in the new study are particularly sensitive to the chromosphere, where substantial flare-related energy deposition occurs.

Ground-based telescopes cannot easily perform comparable observations across much of the near-ultraviolet spectrum because Earth’s atmosphere absorbs ultraviolet radiation.

SUIT therefore provides Indian and international solar researchers with observational capabilities that are difficult to reproduce from terrestrial observatories.

By combining these ultraviolet measurements with simultaneous X-ray data from SoLEXS and HEL1OS, researchers can trace energetic processes across different atmospheric layers.

One of Aditya-L1’s First Systematic Pre-Flare Studies

ISRO describes the work as one of the first systematic investigations using simultaneous ultraviolet imaging and X-ray observations from a single solar observatory to examine pre-flare activity.

The combination is scientifically valuable because solar flares are inherently multi-layered phenomena. Changes in magnetic structure can manifest differently in the photosphere, chromosphere and corona, while particles accelerated during an eruption produce radiation across a wide range of wavelengths.

Studying only one part of the electromagnetic spectrum therefore provides an incomplete picture.

Aditya-L1’s multi-instrument design allows researchers to investigate relationships between these different signatures and reconstruct how energy moves through the solar atmosphere before and during an eruption.

Indian Universities and ISRO Collaborate on the Discovery

The study was led by researchers from the Manipal Centre for Natural Sciences at Manipal Academy of Higher Education, working with scientists from ISRO and other Indian academic institutions.

The research also involved scientists associated with institutions including ISRO’s U R Rao Satellite Centre, the Centre for Excellence in Space Sciences India at IISER Kolkata, the Indian Institute of Space Science and Technology and other participating organisations.

The study was partly supported through an ISRO RESPOND project focused specifically on solar flares, their physics and forecasting for improved understanding of space weather.

This reflects one of the wider objectives of Aditya-L1: providing high-quality observational data not only to ISRO laboratories but also to India’s broader solar-physics research community.

Aditya-L1 Moving from Mission Success to Scientific Discovery

Aditya-L1 was launched aboard PSLV-C57 on 2 September 2023 as India’s first dedicated mission to study the Sun.

After travelling towards the Sun-Earth L1 region, the spacecraft was inserted into its planned halo orbit in January 2024. Since then, its instruments have progressively entered scientific operation and begun producing observations across ultraviolet, visible-light, X-ray and particle-measurement regimes.

The latest solar-flare study demonstrates the transition of Aditya-L1 from a major engineering achievement into a productive scientific observatory.

Its significance lies not simply in India’s ability to position a spacecraft around L1, but in the new science made possible by combining multiple indigenous instruments operating continuously from that location.

Small Solar Events Could Reveal How Major Flares Begin

The broader scientific importance of the discovery lies in what the small brightenings may reveal about the physics leading to major eruptions.

The researchers propose that these chromospheric transients represent small-scale magnetic-energy-release events occurring as the active region moves progressively towards instability.

Rather than viewing a powerful solar flare as an entirely sudden event, the findings support a model in which numerous smaller processes may gradually alter the magnetic environment before a critical transition occurs.

Understanding that progression is central to one of the biggest questions in solar-flare research: determining what transforms a magnetically complex active region into one that is about to erupt.

Aditya-L1’s ability to observe these processes simultaneously in ultraviolet and X-ray wavelengths gives researchers a new tool for answering that question.

A Significant Step for India’s Space-Weather Capability

The latest findings represent one of the most important scientific results yet produced by India’s solar observatory.

The identification of 102 pre-flare transients across seven major solar flares, their concentration around magnetically important regions and the presence of X-ray counterparts in a significant subset provide evidence that measurable changes occur before some major eruptions.

Those observations do not yet allow scientists to issue a precise warning that a major solar flare will occur several hours later. They do, however, identify physical signatures that can now be tested across many more solar events and incorporated into increasingly sophisticated models of flare initiation.

As Aditya-L1 continues observing the Sun through the present solar cycle, its growing archive of simultaneous ultraviolet and X-ray data should allow researchers to examine hundreds of active regions and determine how reliably these pre-flare signatures predict subsequent eruptions.

The result announced on 28 August therefore marks more than an isolated discovery. It demonstrates how India’s first dedicated solar mission is beginning to address one of the central problems in space-weather science: identifying the subtle changes occurring on the Sun before a major eruption becomes visible.

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