Imagine a strong wind, not just any wind, but sunny. This is a constant stream of charged particles, primarily electrons and protons, that the Sun constantly emits into space. This wind, originating from our Sun’s corona, extends far beyond our Earth’s orbit, moving in all directions.

The solar wind shapes the environment of our entire solar system, as it affects the atmospheres of all the planets and helps form things like comet tails.

It plays a crucial role in shaping the magnetic landscapes of planets and celestial bodies by carrying the Sun’s magnetic field through space. ESA’s Solar Orbiter Project Scientist Daniel Müller is one of the experts studying this mysterious solar wind. As you will soon learn, the solar wind has a significant impact on us here on Earth.

Geomagnetic storms and good light

This solar wind interacts with the Earth’s magnetic field, creating geomagnetic storms that can affect satellites, communications systems, and even our power grids. These same interactions also paint the skies near the polar regions with bright, colorful aurorae that have amazed viewers throughout history.

Enter high-tech space missions such as NASA’s Parker Solar Probe and ESA’s Solar Orbiter, which collect detailed data on the speed, density and composition of the intriguing solar wind.

Understanding the solar wind helps scientists predict similar space weather events, warn the public, and mitigate their effects on our technological lifestyle. It also gives us insight into the processes that drive our Sun.

Corona acts like the crown of the Sun

The Sun’s corona, which forms the outer layer of the atmosphere of a large sphere of energy, extends millions of kilometers into space. Compared to the surface of the Sun, which is a photosphere of about 10,000 degrees Fahrenheit, the temperature of the corona exceeds one million degrees.

The mystery of the sharp temperature increase in this distant layer of the Sun arouses the curiosity of our scientists. The corona, which consists of ionized gases commonly known as plasma, is constantly shaped by the Sun’s ever-changing magnetic fields. These magnetic structures create complex patterns that lead to events such as solar flares and coronal mass ejections.

tools of the trade

Studying the Sun’s corona is possible with special instruments such as coronagraphs, which block bright light from the Sun’s surface to see the faint corona. Solar eclipses also provide natural opportunities for direct observation of the corona.

Data from the Solar Orbiter spacecraft equipped with the Metis coronagraph show that small perturbations within the corona grow larger as they move outward, causing a turbulent flow in space. This turbulence interestingly begins in the corona, confirming scientists’ long-standing suspicions.

Turbulence and solar corona

Turbulence in the solar wind affects how the wind heats up and circulates throughout the solar system. It also affects how planets and moons interact with their magnetic fields. This new analysis provides the first evidence of the onset of fully developed turbulence in the Sun’s corona, explains Daniel Müller.

Solar Orbiter’s Metis coronagraph was able to detect it very close to the Sun, closer than any spacecraft that could approach the Sun and take local measurements.

On October 12, 2022, the Solar Orbiter mission took detailed images of the corona from a distance of approximately 27 million miles, less than one-third the distance from the Sun to Earth. Metis blocked direct sunlight and observed dimmer visible and ultraviolet light from the corona, providing clear images of its structure and dynamics.

Understanding solar wind turbulence is critical to predicting space weather that can affect our satellites, communications systems, and power grids. The turbulent solar wind can influence the strength and direction of weather events in space, helping scientists better predict the potential impacts of these events.

Dynamic data captured in video

In the video above, captured by Metis, the Sun appears at the center with a data ring around it showing changes in the brightness of the corona. These fluctuations indicate a change in the density of charged particles and indicate the turbulent movement of particles in the solar wind. The video, repeated three times, shows how these particles behave erratically as they leave the Sun. It was created by the European Space Agency (ESA).

“Observation by Metis of the onset of fully developed turbulence in the solar corona” by Daniele Telloni et al. It was published in Astrophysical Journal Letters.