Class J: Jovian planets are among the most common and familiar
sites in star systems across the universe. These giant spheres of
liquid and gaseous hydrogen, boast extremely dense atmospheres,
and are able to support powerful storms that might endure for
hundreds of years and produce winds in excess of 600 kph.

Many Class J planets also possess impressive ring systems,
composed primarily of rock, dust, and ice.  They form in the cold
zone of a star system, though typically much closer than Class I,
S, or U planets.