Science for All newsletter

What is Helioseismology?

Seismology literally means the study of earthquakes, and the term includes studies of how elastic waves propagate through the Earth and other planet-like bodies, revealing the nature of different layers of the body in question. There are, thus, different types of waves generated by natural quakes as well as explosions made by people. 

In the 1960s waves that resembled this were discovered to exist on the Sun. Further understanding of these waves in the 1970s led to the development of the field known as helioseismology. Today, helioseismology is a technique used to study the Sun. Derived from the words helios (Sun), seismos (quake) and logos (study of), helioseismology is both similar and different from geoseismology, the study of the waves generated by quakes and explosions (seismic waves) and what they reveal about the interior of the Earth. 

A major difference between geoseismology and helioseismology is that while the Earth is a solid, the layers in the Sun are fluid. Hence, there are no shear waves in the Sun. 

The discoveries made using the techniques of helioseismology are far-reaching. Worth noting is its role in understanding the so-called solar neutrino puzzle. A measure of the luminosity of the Sun, or light emanating, suggests that the flux of neutrinos flowing out from it be a certain amount. However, what was observed was markedly different. This discrepancy between the predicted and observed solar neutrino flux was a problem that baffled particle physicists. A breakthrough contribution of helioseismology was when it was shown that this flux could not be due to a flaw in stellar models but this had to be a particle physics problem. Soon a solution using neutrino oscillations – a process by which neutrinos of one type change into other types – was found. 

A more general, related field is asteroseismology, which looks at oscillations on distant stars. The techniques differ a bit from Helioseismology.

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