Invite children to provide a commentary, explaining what that clip shows about the Earth, Moon and Sun. Replay the clip several times, to allow different children to rehearse and extend this commentary. Ask: "What do you think it is like on the Moon?" and "Why does the astronaut need a space suit?" Establish that there is no air on the Moon. Children could try to copy the bouncing way the astronaut moves in the clip. Tell the children that they would find it easier to jump much higher on the Moon, because the "pull" of the Moon is much less than the "pull" of the Earth. Children could try jumping to feel the Earth's pull, bringing them back to the ground. Tell them, "The word we use for that pulling you can feel is 'gravity'."