The next flight was again one powered by an Atlas booster. This flight, MA-2, was fully successful, testing the capsule's heat shield. At the center of the sun there is a nuclear furnace that operates by converting hydrogen into helium-the process of nuclear fusion. This reaction releases the energy which makes the sun shine. At the center of the sun, the temperature is about 20 million degress.
Thermonuclear fusion requires high temperatures and densities to proceed.
The energy at the center eventually finds its way to the surface. Near the surface of the sun, called the photosphere, there is a region called the convection zone. The sun also has a magnetic field, and because the sun is not a solid body, but one that is completely gaseous, it rotates in a peculiar way-differential rotation. The differential rotation, combined with convection, act to create magnetic storms. These are visible as sunspots on the photosphere.