The Vogons, a race of bureaucratic and unpleasant aliens, are constructing a hyperspace bypass for their own purposes. Earth is located in the exact spot they need, and they have no regard for the planet or its inhabitants.
The destruction is swift and unexpected, with the Vogons giving Earth's inhabitants just 15 minutes' notice before vaporizing the planet to make way for the bypass. This sudden and seemingly pointless destruction is part of the novel's absurdist humor and is a central theme to the story.
