The Sun

The big burning ball of gas that holds nine major planets in orbit is not unlike many stars in the universe. The Sun makes up 99.86 percent of the solar system's mass and provides the energy that both sustains and endangers us. Scientists have lately begun calling its tremendous outpouring of energy "space weather." The Sun can be divided into three main layers: a core, a radiative zone, and a convective zone. The Sun's energy comes from thermonuclear reactions (converting hydrogen to helium) in the core, where the temperature is 15 to 25 million degrees. The energy radiates through the mi…