Sun's Structure Shown below is a diagram of the layers of the Sun (both interior and atmosphere). Fill in the following blanks about a few key features of the Sun's structure: - When a star is plotted on the HR diagram, the temperature that we measure to plot it is the temperature of its - It takes longest for light energy to travel through the - Mixing of material happens within the star within the , but does not bring fresh fuel into the because the is in the way. - The energy of the star is produced as radiation by nuclear reactions in the.