MovieBuff09

Chosen answer: Yes, they were intended as coordinates for the aliens to land and begin their invasion. Merrill comments on this while engrossed in the television coverage of the invasion.

Brenda Elzin

Answer: It's left unclear, though the film proposes several possible theories, and there are other possible explanations as well. One major theory brought up in the film is that the aliens were there to acquire Earth's resources after using up their own. Another theory proposed at the end of the movie is that the aliens wanted humans for whatever reason, as a radio DJ mentions seeing his friend's family being dragged away. There is also a very popular fan theory that the aliens are supposed to represent demons that are merely there to create chaos and test the moral strength of humanity, as the film is ultimately about Graham losing and then regaining his faith, although this is more subtext than anything and may not be literally true.

Answer: Near the end of the movie... The morning after in the basement... The guy on the radio says the aliens were there not for the planet, but to harvest humans. For what purpose is unknown, maybe as an energy source, Matrix-style.

Chosen answer: According to the theory in the movie they were there to take the planet for their own because they used up all the resources their own planet. They left the planet when it became apparent to them that the water on Earth was too dangerous.