The Sun is a star, an object in space that makes its own light and heat energy. Energy gives something the ability to do work. Light energy does the work of making things visible, and heat energy does the work of making things warm. The Sun is so huge that a million Earths would fit inside, and instead of being made of rocks and soil like Earth, the Sun is made of helium gas and hydrogen gas. The Sun is very hot and produces its light energy and heat energy when hydrogen and helium atoms rearrange in a nuclear reaction. (Atoms are defined.) The Sun's energy makes life possible on Earth, which is the right distance from the Sun to have the right temperatures for living things to exist. Plants use the Sun's light energy to grow and make sugar for food, and the sugar made by plants also feeds all the animals. Astronomers continue to study the Sun and how it works. Pronunciation guide included. 24 pages filled with engaging, colorful illustrations. Reading Level 1-3, Interest Level 2-5, Word count 322, Lexile measure 540L.