Solar Storm

India's first space-based solar observatory, Aditya-L1, has helped scientists uncover an important detail about how powerful eruptions from the Sun develop as they move into space. New research based on the spacecraft's observations shows that these enormous bursts of solar material do not always spread evenly in every direction. Instead, they can expand asymmetrically, forming tilted and irregular structures.

The finding could improve scientific understanding of space weather and help researchers develop better methods to estimate how solar eruptions travel towards Earth. Such predictions matter because powerful solar events can disturb satellites, radio communication, navigation systems and other technologies that depend on conditions in space.

The research was conducted by scientists at the Indian Institute of Astrophysics (IIA), Bengaluru, an autonomous institution under the Department of Science and Technology. The team combined observations from Aditya-L1 with images from NASA's Solar Dynamics Observatory (SDO) and computer-based three-dimensional modelling.

The study was published in The Astrophysical Journal Letters and examined a coronal mass ejection (CME) observed on August 5, 2024.

A solar eruption that did not behave like a symmetrical bubble

A coronal mass ejection is a large release of plasma and magnetic field from the Sun's outer atmosphere, known as the corona. These eruptions can send vast quantities of electrically charged material into interplanetary space.

Scientists have often used simplified models in which a CME expands outward in a relatively symmetrical, bubble-like form. Such models help explain the general movement of solar material, but they may not capture every detail of an actual eruption.

The August 2024 event provided evidence of a more complicated process. Researchers found that the eruption expanded unevenly and had an inclined structure. A model assuming equal expansion in all directions could not reproduce the observations, while a model incorporating a tilted axis and unequal sideways expansion produced a much closer match.

This distinction is important because the shape of an eruption can influence how it moves through the surrounding solar wind.

How Aditya-L1 detected movement invisible in ordinary images

A major contribution came from the spacecraft's Visible Emission Line Coronagraph, known as VELC. The instrument observes the Sun's corona and studies light emitted by highly heated material.

The research team used a technique called Doppler spectroscopy to understand the movement of plasma. When material moves towards an observer, the wavelength of its emitted light shifts towards the blue end of the spectrum. When it moves away, the wavelength shifts towards the red end.

VELC recorded two distinct spectral features during the eruption. These indicated that different portions of the expanding solar material were moving both towards and away from the spacecraft's viewing direction.

Images from NASA's Solar Dynamics Observatory showed how the eruption spread across the plane of the sky. Aditya-L1's spectroscopic measurements added information about movement along the line of sight. By combining these different observations, scientists could reconstruct a more complete three-dimensional picture of the event.

The researchers then developed a geometric and kinematic model to test possible explanations. The model showed that a tilted CME structure with uneven lateral expansion could reproduce the unusual spectral pattern much more successfully than a symmetrical expansion model.

Why the discovery matters for Earth

The shape of a coronal mass ejection is not simply a visual detail. It can influence how the eruption interacts with the solar wind as it travels through the heliosphere, the region of space dominated by the Sun's influence.

Different parts of an irregular eruption may experience different levels of resistance, or drag, from the surrounding solar wind. This can change the speed at which the material travels and affect estimates of when it might reach Earth.

Accurate arrival-time predictions are important for space-weather monitoring. If a CME is directed towards Earth and carries a strong magnetic field, its interaction with Earth's magnetosphere can trigger a geomagnetic storm.

Depending on its strength and orientation, such a storm can affect satellite operations, high-frequency radio communication, navigation signals and electrical power infrastructure. It can also increase radiation exposure risks for astronauts and spacecraft operating in space.

However, the latest research does not establish that the August 2024 eruption caused a major impact on Earth. Nor does it indicate that a powerful solar storm is about to strike the planet. Its importance lies in improving the understanding of how solar eruptions develop close to the Sun and how their movement can be estimated.

Aditya-L1's role in solar research

Launched by the Indian Space Research Organisation in September 2023, Aditya-L1 is India's first dedicated space-based solar observatory. It operates around the Sun-Earth L1 point, approximately 1.5 million kilometres from Earth towards the Sun.

This location allows the spacecraft to observe the Sun continuously, giving researchers an uninterrupted view that is valuable for studying solar activity and changes in the corona.

The mission carries seven scientific payloads designed to investigate different aspects of the Sun. VELC is its primary payload and is specifically designed to study the solar corona, including the early stages of coronal mass ejections.

The latest study demonstrates the value of combining spectroscopy with conventional imaging. Images can show where an eruption is spreading across the sky, while measurements of wavelength shifts can reveal whether material is moving towards or away from the observer. Together, these techniques provide a richer picture of the event.

What scientists will investigate next

Researchers plan to apply the technique to additional coronal mass ejections. Studying a larger number of events will help establish how consistently VELC can reconstruct the three-dimensional structure, direction and speed of solar eruptions from a single viewing position.

This could eventually contribute to more reliable space-weather models. Better information about the early shape and movement of a CME may help scientists refine estimates of its journey through space and assess possible effects on Earth.

For India, the result also highlights the growing scientific contribution of Aditya-L1. The mission is not only observing solar activity but also providing measurements that can test existing scientific assumptions.

The central message from the research is that solar eruptions are more complex than simplified models may suggest. Understanding their changing shape near the Sun could become an important part of improving forecasts of space weather and protecting the technology that modern societies increasingly depend on.