A Balloon Telescope Finds Hidden Magnetic Threads Above the Sun's Calm Regions

Even the calm parts of the Sun are laced with intricate magnetic structures, according to a new study of observations from a telescope that flew on a high-altitude balloon. ScienceDaily reported that the findings could help explain how energy moves up through the Sun's atmosphere and heats it.

An international team led by the National Astronomical Observatory of Japan used the Sunrise-III observatory, which rose into Earth's stratosphere in 2024. It found thin, thread-like magnetic features that had previously been hard to observe.

What the telescope found above the quiet Sun

Sunrise-III detected numerous narrow, elongated magnetic structures woven into a larger network of magnetic fields above a quiet region of the Sun. That network is known as the magnetic canopy. It forms as magnetic fields concentrated at the visible surface, called the photosphere, spread outward and arch up into the chromosphere, the layer of the solar atmosphere above it.

Researchers had not expected the canopy to look like this. Rather than a smooth, evenly expanding structure, it turned out to contain many fine threads.

To work out how the threads form, the team ran computer simulations that reproduced the patterns Sunrise-III recorded. The results suggest that motions on the Sun's surface twist the magnetic field lines, creating the elaborate structures seen higher up.

The observatory also looked at a second quiet region near the solar limb, the visible edge of the Sun. There it measured magnetic fields inside spicules, which are narrow jets of solar material that shoot up from the surface. Those measurements showed how the distribution of magnetic fields changes with height.

Why the quiet Sun is hard to study

Scientists call areas without prominent features such as sunspots quiet. They cover most of the Sun, which makes them important for understanding how the star behaves overall.

Quiet does not mean magnetically inactive, though. The magnetic fields in these regions are generally weaker than in more active areas, and their fine details are difficult to measure. Telescopes on the ground struggle in particular, because turbulence in Earth's atmosphere blurs small features.

How a balloon helps

Sunrise-III is an international project built around a 1-meter telescope carried by a balloon. During the 2024 mission it floated about 35 kilometers (about 22 miles) above Earth, where atmospheric interference is greatly reduced.

The gondola carried three scientific instruments developed with contributions from several countries. One of them, SCIP (Sunrise Chromospheric Infrared spectroPolarimeter), is a near-infrared instrument developed under the leadership of the Japanese observatory. It is designed to measure magnetic fields continuously across layers of the solar atmosphere, from the photosphere to the chromosphere. That let researchers follow how magnetic structures extend and change with altitude instead of looking at a single layer.

What this means for understanding the Sun

One long-standing puzzle is how the Sun's atmosphere is heated. The new observations show that the chromosphere holds far more intricate magnetic structure than a simple expanding canopy would suggest. Understanding those structures could help scientists trace how energy generated by motions near the surface is passed to higher layers.

According to the report, the discovery is an important step toward explaining how magnetic activity contributes to heating the Sun's atmosphere, including in regions that look calm from afar. It does not settle the question. The simulations point to surface twisting as the likely cause of the threads, and further observations will be needed to confirm how much they matter for heating.

Around Prague, based on reporting by ScienceDaily