A balloon at 35km found threads in the Sun's quietest places
What happened
Astronomers have mapped the magnetic field above a calm stretch of the Sun's surface and found it is far from calm. It is threaded with thin, web-like magnetic structures. The research was led by the National Astronomical Observatory of Japan, part of the National Institutes of Natural Sciences, with an international team. It was published in The Astrophysical Journal Letters and reported more widely on 24 October 2026. The lead author is M. Kubo. The observations came from Sunrise-III, which is not a satellite but a balloon. It carries a one-metre telescope and flies in the stratosphere, at around 35 kilometres up — roughly 22 miles. That altitude puts it above most of the air that blurs images for telescopes on the ground, without the cost and risk of launching into orbit. The flight used for this work took place in 2024. The instrument that made the measurement is called SCIP, short for Sunrise Chromospheric Infrared spectroPolarimeter. It was developed under Japanese leadership and measures magnetic fields across different layers of the Sun's atmosphere, from the visible surface up into the layer above it. The team studied what is known as the magnetic canopy. At the Sun's visible surface, magnetic field is concentrated into small patches. As it rises, it spreads outward and arches over, forming a canopy across the layer above, called the chromosphere. The expectation was something broadly smooth. What the observations showed instead was a canopy full of many narrow, thread-like features. The team also measured magnetic fields inside spicules — narrow jets of solar material that shoot up from the surface — in a quiet region near the edge of the Sun's disc, and mapped how the field changed with height. Computer simulations reproduced the observed patterns. They suggest the mechanism: motions on the Sun's surface twist the magnetic field lines, and that twisting creates the thread-like structures higher up. The researchers summed up the finding simply. Even the Sun's seemingly quiet regions contain elaborate magnetic structures. Or, more bluntly: quiet does not mean magnetically inactive.
Why this matters
Most of the Sun, most of the time, is quiet. Sunspots and flares get the attention, but the regions between them cover far more of the surface. Those quiet regions have weaker magnetic fields than active ones, and that makes them genuinely hard to study. Weak fields produce faint signals, and faint signals get lost in the wobble that Earth's atmosphere adds to ground-based telescope images. So the parts of the Sun that make up most of it have been among the least well measured. That matters for a long-standing puzzle. The Sun's surface is about 5,500 degrees Celsius. The thin atmosphere above it, the corona, is far hotter — hundreds of thousands to millions of degrees. Heat is not supposed to flow from cooler to hotter. Something must be carrying energy upwards and dumping it there. Magnetic fields are the leading suspect, and the canopy is part of the route that energy would take. Finding that the canopy is a web of fine threads rather than a smooth arch changes the picture of how energy moves through it, because thin structures and sharp boundaries are exactly where magnetic energy tends to be released. There is also a practical thread, so to speak. The Sun's magnetic activity drives space weather, which affects satellites, GPS signals, radio communications and, in severe cases, power grids. Better physics of how magnetic energy moves through the solar atmosphere eventually feeds into better forecasting of all that. And there is the quieter point about method. This result came from a balloon. Not a spacecraft, not a mountaintop observatory. A telescope hung under a balloon in the stratosphere for a matter of days.
What the evidence actually says
This is an observational result with a simulation attached, and both parts have limits worth naming. The observation covered one quiet region, near the edge of the Sun's visible disc, during one balloon flight in 2024. Looking near the edge is deliberate — it lets you see structures side-on and measure how things change with height — but it also means the geometry is unusual and the results need checking elsewhere on the disc. The simulations reproduced the observed patterns and offer an explanation: surface motions twisting field lines. That is a strong form of support, because a simulation that produces the same thing you measured from independent physics is more convincing than one tuned to match. It is still a model. It shows that twisting surface motions can generate such structures, not that this is the only way they could arise. The paper is in The Astrophysical Journal Letters, which publishes shorter, timely results. That is a well-regarded venue, and it is also a format that invites follow-up rather than closing a subject. What the study does firmly establish is a measurement that was previously very difficult to make: the three-dimensional magnetic structure of a quiet solar region, including inside spicules, across layers from the visible surface into the chromosphere. The finding that this structure is finely threaded rather than smooth is a direct observation, not an inference. The connection to coronal heating is the part to hold loosely. The researchers say the results contribute to understanding how magnetic activity and energy from the surface feed the upper atmosphere and help heat it. Contribute is the right word. The heating problem has been open for about eighty years and will not be closed by one flight.
What to know
Using the balloon-borne Sunrise-III observatory, flying at about 35 kilometres with a one-metre telescope and the Japanese-led SCIP instrument, astronomers mapped the magnetic field above a quiet region of the Sun. They found the magnetic canopy — the layer where surface magnetic fields spread out and arch over the chromosphere — is made of many thin, thread-like structures rather than being smooth and uniform. They also measured magnetic fields inside spicules, the narrow jets of solar material, and tracked how the field changed with height. Computer simulations reproduced the patterns and suggest surface motions twisting field lines are the cause. Quiet regions cover most of the Sun and are hard to measure because their fields are weak and ground-based images are blurred by the atmosphere. The work feeds into the long-standing question of how the Sun's outer atmosphere gets so much hotter than its surface, and into space weather forecasting. It is one region, from one flight, and needs confirming elsewhere. Sources: The Astrophysical Journal Letters, "Three-dimensional Magnetic Field Structure of a Quiet-Sun Region Revealed by SUNRISE III/SCIP", Kubo M et al., 2026, volume 1008 issue 1, L9, DOI 10.3847/2041-8213/ae909b, https://doi.org/10.3847/2041-8213/ae909b; ScienceDaily, "Astronomers uncover a mysterious magnetic web above the Sun", 24 October 2026, https://www.sciencedaily.com/releases/2026/10/261023023723.htm; National Astronomical Observatory of Japan, https://www.nao.ac.jp/en/. This article is for general information. It covers astronomy research and contains no health advice; for any health question, speak to a doctor, pharmacist or other qualified healthcare professional.
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