Blue Peter presenters Helen Skelton and Barney Harwood want to learn more about the solar system so they challenge scientists Helen Czerski and Jem Stansfield to find out more. They look at how to make telescopes and rockets, and use a toilet roll to measure the distances between planets.
| Actor | Role |
|---|---|
 Helen SkeltonHerself - Presenter | Herself - Presenter |
 Barney HarwoodHimself - Presenter | Himself - Presenter |
 Helen CzerskiHerself | Herself |
| JJem StansfieldHimself | Himself |