On June 1, 2022, light and waves from the Sun’s corona helped researchers sketch its magnetic field in three dimensions, including regions hidden beyond the Sun’s visible edge. The map came not from a new telescope, but from a fresh way of reading observations already collected at Mauna Loa Solar Observatory in Hawaii.
The corona is the Sun’s hot outer atmosphere. Scientists have watched its changing shapes for decades, but measuring the magnetic field that guides those shapes has been a stubborn gap. That field helps drive solar eruptions, which can send bursts of energy and particles toward Earth. Severe space weather can disrupt technologies people rely on, including critical infrastructure. Better measurements could help scientists build stronger models and improve forecasts.
The research team combined a method for making global, two-dimensional maps with a technique called IQUD inversion. In simple terms, the technique pulls information from waves moving through the corona to estimate the magnetic field’s strength and direction in three dimensions. The team applied it to observations from two instruments at Mauna Loa Solar Observatory: the original Coronal Multi-channel Polarimeter, or CoMP, on October 14, 2016, and its upgraded version, UCoMP, on June 1, 2022.
The result is the first observational demonstration of this approach to mapping the corona’s three-dimensional magnetic field. The work was led by Alin Paraschiv of the U.S. National Science Foundation National Solar Observatory, with researchers from the National Science Foundation National Center for Atmospheric Research and Southwest Research Institute. Daniela Lacatus, a co-author and researcher at the National Center for Atmospheric Research, said the maps show both the field’s strength and its 3D direction in the regions covered by the observatory’s data.
The advance is promising, but it is not yet a ready-made forecast tool. The first maps have limits, and scientists say the method needs more development and validation before it can be used routinely. The team has made its software and data sets public so other researchers can test the results, improve the method and try it on suitable observations from other days.
That openness may help turn a research demonstration into a practical way to study the forces behind solar eruptions. Mauna Loa Solar Observatory director Tom Berger said the work points toward future observations from the advanced COSMO coronagraph network, planned as a follow-on to the current facility. The researchers hope the method will eventually become a standard data product in that network. For now, the maps offer scientists a new view of a hidden part of the Sun—and a path toward understanding the space weather it can send our way.