The term 'Star of Earth' is a reference to the SUN, which is the star at the center of our Solar System. The SUN is a massive ball of hot gas that provides light and heat to the planets in our Solar System, including Earth. It is composed mostly of hydrogen and helium and has a diameter of about 864, 400 miles. The SUN is the most important source of energy for life on Earth, and its gravity holds the Solar System together.