Perhaps just the stamps from one particular planet or one specific system?

He knew they were planning to build off their world, but on this particular planet?

These factions were centered on a particular planet or system.

Opponents square off against each other on a particular planet and fight to control all of its nations.

What brought up this odd notion of a particular planet from which we all started?

Because he was the only one to step forward and point us to a particular planet?

Chellish had taken it upon himself to give names to the system and the particular planet they were concerned with.

It was one reason for selecting this particular planet.

Inevitably, the four human temperaments were seen to be subject to a particular planet.

They could have given many reasons why this particular planet had been selected.