The Solar System What is the solar system? It is our Sun and everything that travels around it Our solar system is elliptical in shape That means it is shaped like an egg The Sun is in the center of the solar system Our solar system is always in motion Eight known planets and their moons, along with comets, asteroids, and other space objects orbit the Sun The Sun is the biggest object in our solar system It contains more than 99% of the solar system's mass Astronomers think the solar system is more than billion years old Astronomers are now finding new objects far, far from the Sun which they call dwarf planets Pluto, which was once called a planet, is now called a dwarf planet What is the solar system? What shape is our solar system? Where is the Sun located in the Solar system? How many planets orbit the Sun? How old is the solar system thought to be? The Planets and Dwarf Planets A planet is a large space object which revolves around a star It also reflects that star's light Eight planets have been discovered in our solar system Mercury, Venus, Earth, and Mars are the planets closest to the Sun They are called the inner planets The inner planets are made up mostly of rock The outer planets are Jupiter, Saturn, Uranus, and Neptune Jupiter, Saturn, Uranus, and Neptune are large balls of gases with rings around them All eight planets travel around the Sun in a different orbit In its orbit, there are not many other objects like the planet Dwarf planets are objects that are similar to planets except that they orbit the Sun in areas where there are many similar objects