A star is a huge ball of hot, glowing gases, which whirls in space. All stars are made up of the same two gases, hydrogen, and helium, and they shine by their own light, which is produced as a result of atomic reactions in their center, causing great heat.
Planets are different. A planet is much smaller and more solid than a star. It does not shine by its own light, because it is not nearly hot enough to produce that light. Instead, it shines by the light of the nearest star.
Our sun is a star, and in its solar system, there are nine planets – Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto.
