PHI's map of the Sun's magnetic field

This image shows the line-of-sight direction of the magnetic field on the Sun's disc. This kind of map is also called a ‘magnetogram’. It was measured by the Polarimetric and Helioseismic Imager (PHI) onboard the Solar Orbiter spacecraft on 22 March 2023.

This map shows that the Sun's magnetic field is concentrated within and around sunspots. It either points outward (red) or inward (blue) wherever the sunspots lie. Elsewhere the magnetic field is much smaller, indicated by grey (no magnetic field), yellow or green (small magnetic field). The strong magnetic field inhibits convection in the Sun, because charged particles are forced to follow the magnetic field rather than following the heat-mixing convective flow. As a result, sunspots are colder than their surroundings.

Assembled from multiple high-resolution images taken by the PHI instrument, the diameter of the Sun's disc is spanned by around 8000 pixels. It is one image of a set of four, three being the first high-resolution full-disc views of the Sun from PHI and the fourth an image of the Sun's corona taken by Solar Orbiter's Extreme Ultraviolet Imager (EUI).

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