Did You Know?
The plot hinges on the relatively small piece of the asteroid which remains embedded in the moon being of very high mass, due to its high density as a piece of a brown dwarf. In fact, the only reason the density of a brown dwarf is so high is because of the dwarf's large mass, which generates such a high gravitational field it compresses the mass. If a piece of it is removed from the gravitational field, it will expand until its density is that of normal matter, much as compressed air taken out of the tank no longer remains compressed. See more
References The Jetsons