A team of researchers has produced the first global, three-dimensional estimates of the Sun’s magnetic field, including the area beyond the Sun’s visible edge. This breakthrough marks an important step towards more accurate models of solar activity — and ultimately, better predictions of solar magnetic eruptions which are the root cause of extreme space weather that can impact critical infrastructure technologies on Earth.
Scientists have been able to observe the structure of the Sun’s upper atmosphere – called the corona – for decades but haven’t been able to measure the full magnetic field responsible for shaping it. Now, a new study demonstrates a way to fill that gap by applying a new method to existing observations from the Mauna Loa Solar Observatory (MLSO), which is operated by the U.S. National Science Foundation National Center for Atmospheric Research (NSF NCAR).
The method of reconstructing the Sun’s elusive 3D coronal magnetic field by extracting previously inaccessible information from these observations is published today in The Astrophysical Journal Letters .
“By applying a novel method to observations from the Mauna Loa Solar Observatory, we produced the first determinations of the coronal magnetic field's strength and 3D direction across the regions where MLSO observations are available,” said Daniela Lacatus, an NSF NCAR researcher and one of the paper’s co-authors. “These results help to overcome a major bottleneck in measuring the coronal magnetic field that has persisted for decades.”
The study was conducted by researchers from NSF NCAR, the U.S. National Science Foundation National Solar Observatory (NSF NSO), and Southwest Research Institute. The research was funded by the National Science Foundation.
Going from 2D to 3D
To create the 3D maps of the coronal magnetic field, the research team built on two previous research endeavors: a study that produced the first 2D global maps of the coronal magnetic field,using data from an instrument called the Upgraded Coronal Multi-channel Polarimeter (UCoMP) located at MLSO, and a novel technique known as the IQUD inversion . The IQUD inversion has shown promise in both theoretical and statistical tests.
Combining the two methods, the research team focused on using data from the original Coronal Multi-channel Polarimeter (CoMP) on October 14, 2016 and UCoMP on June 1, 2022. The result was the ability to pull out information encoded in waves traveling through the corona to reconstruct the 3D coronal magnetic field.
“For the first time, we can begin to see the Sun’s hidden magnetic architecture in three dimensions not by building a new type of ground or space instrument, but by decoding the light and waves already coming from the Sun’s corona,” said Alin Paraschiv, an NSF NSO researcher and the study’s lead author. “For a star whose magnetic activity influences everything from the solar wind to the auroras dancing across Earth's skies, being able to measure more of that hidden architecture could transform our understanding of how the Sun works.”
While the study represents the transition from a theoretically demonstrated technique to an observationally demonstrated capability, the initial magnetic-field maps have limitations. Additional development and validation will be necessary before the approach can become a routine capability. To encourage that progress, the team has made its analysis software and datasets openly available, allowing other scientists to test, refine, and extend the method.
“It's very exciting to see MLSO data used as a pathfinder to advance our ability to predict solar eruptions,” said Tom Berger, MLSO director. “The team has done an amazing job at demonstrating how our advanced COSMO coronagraph network – the follow-on to the current MLSO facility – will enable new observations of the Sun's magnetic field, filling a critical gap in our observations of space weather drivers.”
MLSO data from CoMP and UCoMP are publicly available. Researchers should be able, in theory, to generate 3D coronal maps applying the IQUD inversion from any day that suitable observations are available from either instrument.
The method developed by Paraschiv and his colleagues is openly available , but has not yet been integrated as a data-product into operational observatory pipelines. They hope that it will one day be a standard data product in the advanced COSMO observatory network.
“When we did the validations, we were so excited to see that the results look reasonable and comparable to what we’d expect,” said Lacatus. “People have already told us how excited they are about this and we really want them to come test the method to help us see where it can be tweaked and refined. We’ve proved the method can work and now we just need to make it broadly available to the community.”
The Astrophysical Journal Letters
Observational study
Not applicable
A First Global Full-vector Coronal Magnetic Field Inference Using MLSO CoMP and UCoMP Observations
28-Oct-2026