There are eight planets in the Solar System,and each one is very diffirent. Some planets, like Jupiter and Saturn are very large. Others like Mercury and Mars are smaller. Jupiter has moons that are larger thanMercury. The planets also have diffirent atmospheres. Urabus, Jupiter and Saturn have atmospheres of hydrogen abd helium. The atmosphere on Venus is made up of carbon dioxide. Earth has a nitrogen and oxygen atmospheres. Neptune's atmospheres is mostly hydrogen. The planets also have diffirent temperatures. Uranus is the coldest and Venus is the hottest