Once they were past the outer planets, though, he did find all that open space a little scary.

However, such objects could be associated with outer planets as well.

The outer planets of the system have not yet been explored.

And the outer planets are so far away that I think we had better wait till later trips.

Penalty of spending too much time on the outer planets.

This will be the closest any spacecraft has come to one of the outer planets.

This whole nothing town was typical outer planets: a right mess.

We're here to bring the Word to the outer planets.

The outer planets are retrograde for over 40% of the time.

He also indicated the existence of two additional outer planets.