An alien spirit tries learning about humans by possessing boys, and has a bad time of it.
A misfit member of an organization of time travelers flubs a trip and yanks a kid from 1982 back in time.
It's an odd combination of brains and bubblegum; well-acted, fast-and-loose and interesting.
The world is invaded and destroyed by a vastly superior force of aliens, and survivors barely hold on to resistance.
See also Farscape - (1999 show), which also has a living ship with a crew that wanders around.