That brings me memories of Cosmos 1999. The moon left Earth's orbit to outer space because explosions, but being slingshoted away because a nearby massive enough object passing by looks like a more possible scenario, not explored enough by sci-fi.
The basic premise of the show that an explosion at a nuclear waste dump could produce enough energy to push the Moon out of the Solar System to wander the galaxy is an interesting product of its time. Concerns over the power of nuclear explosions was high and casual access to knowledge about the plausibility of such a scenario was somewhat limited.
There's a fan driven update called Space: 2099 that improves some of the more dated aspects of the show, including showing the Moon enter some type of portal or wormhole to make suspension of disbelief easier. While the Special Edition releases of Star Wars often suffered from updating certain aspects, especially special effects, the Space: 2099 changes were generally good for the show. Too bad they're unable to fund raise enough and get permission to do the entire series.
Space: 1999. Do you happen to be french or polish?
In Germany they called it "Mondbasis Alpha". As I child I really liked this series and it's predecessor UFO made by the same team (Gerry and Sylvia Anderson of Thunderbirds fame).
