How does helioseismology help scientists study the Sun’s interior?

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Sun Joshua trees at sunset, Joshua Tree National Park, southern California, U.S.

Helioseismology is a scientific method analogous to geoseismology that allows researchers to map the Sun’s internal structure by measuring the frequencies and wavelengths of waves at its surface.1

Unlike Earth, where waves are triggered by earthquakes, solar oscillations are continuously excited, likely by currents within the convective zone. Scientists analyze these oscillation patterns, or modes, to gain insights into the solar interior:1

Mapping Depth: Modes with few nodes allow sound waves to travel deeply into the Sun, while modes with many nodes are restricted to outer regions. By compiling thousands of these mode frequencies, scientists can develop independent solar models that match observed oscillations.1
Measuring Rotation: Because the Sun rotates, the Doppler effect causes frequency splitting in these modes. Since different modes reach varying depths, researchers can map rotation throughout the solar interior, revealing that the region below the convective zone rotates as a solid body.1
Magnetic Field Insights: Helioseismology helps study the differential rotation generated by the convective zone, which is believed to be critical in the generation of the Sun’s magnetic field.1