Transcript: From ancient times Chinese and Indian astronomers noticed and recorded sunspots, blemishes or dark spots on the surface of the Sun. This work improved in the 1600s with the invention of the telescope which allowed the counting and tracking of sunspots. Galileo used such observations to prove that the Sun was not a perfect sphere, a decisive break in the tradition of Greek ideas. Unfortunately, through his long and careless observations of the Sun, Galileo ended his life blind. Four hundred years of sunspot observations have allowed us to show the way that the Sun rotates. The rotation period of the Sun is 25.4 days at the equator relative to the stars, 27.3 days relative to the Earth because the Earth moves around the Sun while the sun rotates. The Sun rotates differentially, meaning that the rotation of 25 days at the equator is faster than the rotation of the poles which takes about 33 days. This is proof that the Sun is gaseous and not solid.