TheSunis herounder natural object measured so far. In fact, if it were resized to the scale of a beach ball it would be so “perfectly” spherical that the difference between the widest and the narrowest diameter would not exceed the thickness of a human hair. To be more exact, if the diameter of the solar sphere measured one meter, its equatorial diameter would be only 17 millionths of a meter greater than the diameter that crosses it from the north pole to the south pole, which also coincides with its axis of rotation.
Scientists have been trying for half a century to study the exact shape of the Sun with all kinds of instruments. Now researchers from the University of Hawaii, Stanford University and the University of Ponta Grossa (Brazil) seem to have achieved thanks to the Helioseismic and Magnetic Imager (HMI) of theSolar Dynamics Observatory(SDO for its acronym in English), a NASA solar telescope that obtained its first image of our star in 2010, and since then it has been offering striking portraits of the star king. Thanks to the fact that there is no atmosphere that distorts the image captured by this instrument, the measurements obtained have great precision, as explained by Jeff Kuhn and his colleagues inScience Express, who has spread the news. “For years we have believed that our fluctuating measurements on the Sun indicated that the sphere was constantly changing, but the truth is that its shape does not change; the only changes of the star are those related to its11-year sunspot cycle“, concludes the astronomer.
