Magnetic Field Visualizations
It is the Sun’s magnetic field that primarily determines what we see during a total solar eclipse. For this reason scientists are routinely seeking new ways in which to visualize the incormation encoded in our three-dimensional (3D) models of the coronal magnetic field.
Traditionally, scientists visualize magnetic field by tracing individual field lines and rendering their geometry in a 3D scene. This is shown, for example, on the Energization page. However, one persistent difficulty with this method is choosing which field lines to show, and how to relate those to what we actually see in imaging observations. One alternative, which we pioneered for our 2017 prediction, is to instead compute volume renderings of the magnetic squashing factor (; Titov et al. 2007). is a measure of true- or near-discontinuities in a vector field mapping, which for magnetic fields are known as separatrices or quasi-separatrices. These essentially mark the boundaries between distinct magnetic flux-systems. By visualizing these separatrices in 3D using line-of-sight (LOS) integration, we can construct images that reveal the underlying magnetic skeleton of the solar corona.
The above movies show a pair of brand new squashing factor visualizations that we developed for the 2026 prediction. In the left panel we show a color rendering of that uses masked integrals to separate the closed field (white) from the open magnetic field (colors). The open field is colored by the polarity of its surface footprint (Magenta: positive, Cyan: negative), and the integration is weighted by the Thomson scattering total brightness kernel to emulate what we see in white light. The right panel is missing the closed field component, which helps reveal the complex and 3D nature of open flux bundles in the corona.
Scientifically, closed field lines in the corona generally contain denser plasmas and often correspond to the brightest coronal features that we see during a total eclipse. Open field lines, on the other hand, are the source of the solar wind and interplanetary magnetic flux. Understanding the interplay between the closed corona and the constantly changing footprint of open fields, particularly during CMEs (several of which occur in the simulation and are visualized here) is currently a key topic of study in the field of heliophysics.
Lastly, the bottom panels show various other types of squashing factor renderings, including those shown on some of the other prediction pages. Comparing the right panel (closed field only) to the previous iterations of our renderings (all field types) we see that by using different observation-based weightings we can tease out different features of the 3D magnetic field.
