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.
