In a significant breakthrough for space weather research, scientists have achieved something never done before: near-daily measurements of the Sun’s global coronal magnetic field. This region, where the Sun’s most powerful and disruptive solar storms are born, has previously been observed only sporadically. The ability to now gather consistent and comprehensive data from this area is expected to provide unprecedented insights into the mechanisms behind solar storms, which can pose significant threats to global technologies and infrastructure.
The new data were collected by the Upgraded Coronal Multi-channel Polarimeter (UCoMP), an instrument that observed the Sun over eight months, beginning in February 2022. The results of this groundbreaking study are published in Science, revealing how UCoMP has transformed our ability to monitor and understand the Sun’s magnetic activity.
The Role of the Coronal Magnetic Field
Solar magnetic fields are the driving force behind solar storms, which can disrupt communication systems, power grids, and critical technologies like GPS. However, our understanding of how the Sun’s magnetic field stores and releases energy has long been hampered by the difficulty of measuring it in the corona—the Sun’s upper atmosphere—where solar storms originate.
The magnetic field of the Sun’s corona has been notoriously challenging to observe, due to its weak signals compared to the Sun’s surface, known as the photosphere. Standard polarimetric methods, which allow scientists to observe magnetic fields, typically require large, costly equipment that can only capture limited sections of the corona. However, the advent of UCoMP has allowed researchers to bypass these limitations, offering the ability to observe the Sun’s entire coronal magnetic field in a consistent, global manner.
UCoMP: A New Era in Solar Observation
UCoMP, a much smaller and more affordable instrument than traditional solar telescopes, uses advanced polarimetric techniques to measure the solar corona’s magnetic field. Located at the Mauna Loa Solar Observatory in Hawaii, UCoMP is designed to block out direct sunlight, much like the effect of a solar eclipse, so that scientists can observe the dim outer layers of the Sun.
The real game-changer is UCoMP’s ability to combine coronal seismology with magnetic field measurements, creating a global map of the Sun’s corona on an almost daily basis. Using magnetohydrodynamic (MHD) waves detected by UCoMP, researchers can now map both the strength and direction of the Sun’s magnetic fields.
The new measurements allowed the research team to produce 114 detailed magnetic field maps over the eight months from February to October 2022. This capability marks a major leap forward in solar physics, as previous instruments could only provide irregular snapshots of the Sun’s magnetic behavior.
Filling a Crucial Gap in Solar Storm Prediction
“This is a monumental step in our efforts to understand how solar storms form and evolve,” says Zihao Yang, the lead author of the study and a postdoctoral fellow at the U.S. National Center for Atmospheric Research (NCAR). “Before this, we were missing critical global data about the Sun’s magnetic fields. Now, we can start filling in the gaps and better predict when and where these powerful storms will occur.”
Yang’s research is supported by an international team from Northumbria University (UK), NCAR (USA), Peking University (China), and the University of Michigan (USA). The research received funding from the National Natural Science Foundation of China and the National Key R&D Program of China. The UCoMP instrument itself was developed with support from the U.S. National Science Foundation and is operated by NCAR.
A Collaborative Effort Toward New Discoveries
While UCoMP has made significant strides in observing the Sun’s magnetic field, it complements larger instruments like NSF’s Daniel K. Inouye Solar Telescope (DKIST), the world’s largest solar telescope. With its 4-meter aperture, DKIST allows for highly detailed observations of smaller areas of the corona, whereas UCoMP provides a global view. Together, these instruments offer a more complete picture of the Sun’s magnetic environment, allowing researchers to track the build-up of magnetic energy across different scales.
In 2020, a similar but less advanced instrument produced the first-ever map of the Sun’s global coronal magnetic field. The latest observations made with UCoMP offer far greater detail and consistency, allowing scientists to track how these fields evolve.
One of the most exciting outcomes of this study is the first-ever measurement of the coronal magnetic field at the Sun’s polar regions. While the Sun’s poles remain difficult to observe directly, UCoMP’s enhanced sensitivity allowed the researchers to infer magnetic data from these elusive areas for the first time.
Preparing for Future Solar Storms
As the Sun approaches the peak of its 11-year solar cycle, known as solar maximum, solar storms are expected to increase in both frequency and intensity. UCoMP’s ability to provide daily measurements of the Sun’s coronal magnetic field will be crucial in forecasting these events and mitigating their impacts on Earth. Scientists are hopeful that, by combining UCoMP’s data with other solar observation methods, they will soon be able to produce 3D models of the Sun’s entire magnetic field.
In the future, instruments like UCoMP could play a pivotal role in space weather forecasting, providing advanced warning of solar storms and helping protect critical technologies that underpin modern life. As Yang and his team continue their research, they hope to further refine their models and improve the accuracy of solar storm predictions.
By shedding light on the dynamics of the Sun’s corona, UCoMP is helping scientists unravel the mysteries of our closest star—and in doing so, it may one day help us protect our increasingly technology-dependent world from the dangers posed by solar storms.
