Class J planet

Class J planets range in age from 2 to 10 billion years old. Their diameters range in size from 50,000 to 140,000 km. They are always located in the cold zone region of a star's solar system. Their surfaces are tenuous, comprised of gaseous hydrogen and hydrogen compounds. The atmosphere within the planet vary in temperature, pressure and composition. Hydrocarbon-based life has been known to exist in these planets. ()

The Fairstar hid within the atmosphere of a Class J planet to escape attack from a Cardassian raider.

Class J planets

 * Jupiter (Sol V)
 * Saturn (Sol VI)