The order of the planets from the sun is Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. Before 2006, Pluto was considered to be a planet; as of 2014, it is considered to be a dwarf planet.
Mercury, Venus, Earth and Mars are called the inner planets. These planets are smaller than the other planets and mostly made of rock. Jupiter, Saturn, Uranus and Neptune are the outer planets. They are large balls of gases. An asteroid belt lies between Mars and Jupiter.
A planet is a large object in space that orbits a star and reflects light from that star. As of 2014, scientists have found eight planets in this solar system. Each planet has its own unique orbit. Besides Earth, all planets are named for an ancient Roman deity.
Another class of objects known as dwarf planets was created in 2006. Scientists created this category after discovering new objects in a distant region of the solar system, known as the Kuiper Belt, which were of similar size or larger than Pluto. Dwarf planets must orbit the sun and have enough mass have become round due to their own gravity. Planets have cleared their orbits around the sun so no other similar objects are at the same distance. Dwarf planets fail to do this.