Our Constant Sun

摘要

The exact shape of the Sun provides information on its internal structure. Based on data obtained by the Helioseismic and Magnetic Imager aboard NASA's Solar Dynamics Observatory, Kuhn et al. (p. 1638, published online 16 August; see the Perspective by Gough) measured the solar shape during a 2-year period in which the Sun evolved from a minimum to a maximum of sunspot activity.