The Sun: The sun is a medium sized star and by for the largest object in our solar system. The Earth and all other planets, comets and asteroids of our solar system orbit around it.
The Earth: Earth is our home planet and third planet closest to the sun. Earth is an ocean planet, made up of 70% water and the only planet in our solar system known to harbor life.
Planets: A massive, spherical object in space that orbits a star. In the case of our solar system, we have 8 planets (9 if you count Pluto). A planet must be a certain size to be considered a planet.
Moons: Moons are natural satellites that orbit a planet.
Asteroids: Rocky bodies that orbit the sun. These 'rocks' are too small to be considered planets.
Comets: Small icy objects that orbit the sun. When it is close to the sun, it emits a gas, called a tail.