The Jovian Planets are know as "Gas Giants", because they are mainly made up of helium and hydrogen gases. The term Jovian comes from the word Jupiter. Although the Jovian Planets are composed of hydrogen and helium they are not entirely made up of just gases they also include nickel and can include ice. They are much larger than other planets and form the outer parts of our solar system. There are a total of four Jovian Planets, which include Jupiter, Saturn, Uranus and Neptune. Out of all four of those Jupiter is the largest.

This is a picture that shows all of the four planets that make up the Jovian Planets.