Jupiter

Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. Jupiter is classified as a gas giant along with Saturn, Uranus and Neptune.

It appeared in a photograph Buster took and shown to the Brain in The Boy Who Cried Comet, It is the mission that Arthur Read was going on to when it was cancelled because D.W. was not with him in D.W., the Picky Eater.