Silent storms: Experts identify the mysterious source of solar wind

The Sun, a blazing sphere of energy, has always fascinated scientists. Its intense heat and powerful magnetic fields shape the solar system. Yet, despite decades of research, some of its secrets have remained elusive.

One of the biggest mysteries has been the origin of solar wind – a steady stream of charged particles that flows continuously from the Sun.

This solar wind influences Earth’s magnetic field, disrupts satellites, and even creates stunning auroras. Now, new research confirms that tiny, previously unnoticed jets play a crucial role in launching both fast and slow solar wind.

The European Space Agency’s (ESA) Solar Orbiter mission has provided evidence that these small but mighty jets emanate from across the Sun’s surface, particularly in dark regions known as coronal holes.

This revelation reshapes our understanding of how solar wind is born and how it travels across the solar system.

Tiny jets across the corona

In 2023, scientists made an intriguing discovery near the Sun’s south pole – short-lived jets appear from within coronal holes. These jets, that last only about a minute, eject charged particles at speeds of around 100 kilometers per second.

The research team suspected that these jets contributed to the solar wind but lacked comprehensive evidence to prove their role.

Recent data, however, has provided conclusive proof. By analyzing more observations from the Solar Orbiter, scientists found that these jets emit not just in isolated spots but from coronal holes all across the Sun’s surface.

The latest study confirms that these jets feed both fast and slow solar wind, thus solving a long-standing puzzle in solar physics.

Solar wind: A mysterious force

The solar wind has long been a subject of study. It consists of a continuous stream of charged particles – mostly electrons and protons – that blow outward from the Sun in all directions.

This wind interacts with planets, moons, and interstellar space. On Earth, it shapes our magnetic field, influences satellite communications, and drives the auroras seen near the poles.

Scientists have known that there are two distinct types of solar wind, fast and slow. The fast solar wind originates from coronal holes, where the Sun’s magnetic field stretches outward into deep space. These regions allow charged particles to escape, creating a powerful flow of solar material.

However, the exact mechanism that launches these particles remained unclear. For years, researchers wondered whether small-scale solar activity – such as tiny jets – played a role. Until now, the source of the slow solar wind had remained unknown.

Tracking the source of solar wind

The latest findings provide a breakthrough. A team of scientists, led by Lakshmi Pradeep Chitta at the Max Planck Institute for Solar System Research, examined data from Solar Orbiter’s powerful imaging instruments.

The experts identified numerous small jets emitting from within coronal holes, even those near the Sun’s equator.

By combining high-resolution images with direct measurements of solar wind particles and magnetic fields, the team successfully linked the solar wind detected near the spacecraft to these specific jets.

The surprise was that these jets were not only associated with fast solar wind – they also played a role in the production of slow solar wind.

This marks the first time that researchers have been able to confirm a connection between small-scale jets and both types of solar wind.

Improving space weather forecasting

The finding is significant because it changes how we think about solar wind formation. Until now, theories suggested that different processes might be responsible for the fast and slow types of wind.

But this study shows that the same underlying mechanism – tiny jets emitting from within coronal holes – can launch both types.

Understanding the origins of solar wind is crucial for predicting solar activity and its effects on Earth.

When solar wind interacts with Earth’s magnetic field, it can trigger geomagnetic storms. These storms can disrupt power grids, interfere with GPS signals, and affect satellite operations.

By identifying the processes that give rise to the wind, scientists can improve space weather forecasting and develop better protective measures for satellites and electrical infrastructure.

Flybys with the Solar Orbiter

The breakthrough research was made possible by the sophisticated instruments aboard Solar Orbiter, a collaboration between ESA and NASA.

The spacecraft carries a unique set of tools capable of both capturing detailed images of the Sun’s surface and measuring the charged particles that make up the solar wind.

Solar Orbiter’s close approaches to the Sun, which occur roughly twice a year, allow scientists to gather invaluable data. During its flybys in October 2022 and April 2023, the spacecraft collected crucial information that led to this discovery.

Researchers now plan to analyze future flybys to gain an even deeper understanding of these jets and their role in solar wind generation.

Future of solar research

Although this discovery answers a major question, it also raises new ones. Scientists now want to understand how these jets form and why they launch charged particles at such high speeds.

Future observations from Solar Orbiter, combined with data from other missions like NASA’s Parker Solar Probe, will help researchers piece together a more complete picture of solar wind dynamics.

Instruments such as the Extreme Ultraviolet Imager, Polarimetric and Helioseismic Imager, Solar Wind Plasma Analyser, and the Magnetometer will continue to provide critical insights.

By refining our understanding of the Sun’s powerful events, scientists hope to improve predictions of solar behavior and its impact on space weather.

Tiny jets may be small, but their influence reaches across the solar system, shaping the space environment and our daily lives on Earth.

The study is published in the journal Astronomy & Astrophysics.

Image Credit: ESA

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