Hello
The jovian density is [tex]1.33~g/cm^3[/tex], while the density of terrestrial planets is much higher. For instance, the earth's density is [tex]5.51~g/cm^3[/tex]. The reason of this difference is in the different chemical composition: while jupiter is made of gas (mainly hydrogen), with lower density, while the terrestrial planets are made of solid and liquid, with compounds of higher density.
