Answer to Question 1
D
Answer to Question 2
(1 ) Astronomers create mathematical models that use the laws of physics and the Sun's observed composition, mass, and age to compute its internal conditions. Therefore, we believe that our models are accurate if they can reproduce the characteristics of the Sun that we can observe (such as its radius and luminosity). (2 ) By measuring Doppler shifts of material on the Sun's surface, we observe vibrations of the surface that are created deep within the Sun. We can learn about the densities and other characteristics of the various layers within the Sun by studying how the waves propagate throughout the Sun. (3 ) Another way that we can learn about the interior of the Sun is by detecting solar neutrinos that are produced by the nuclear fusion reactions occurring in the Sun's core.
