The Crystal Gems are in a tight spot. They're stuck on the Moon, and Steven's just been blown out into space. Well, out into the minuscule atmosphere of the Moon, which is just as bad. Humans can survive exposure to space for maybe 90 seconds, but his gem powers will probably keep him safe. He just needs air to breathe.
The solution is obvious: BUBBLE THE MOON.
The Moon will be bubbled at 7:00 ET/PT on Cartoon Network. If you don't have Cartoon Network, just stand outside; the Moon's in First Quarter today. Oh, or there's streams and downloads after the break.