 Why do the aliens believe they have succeeded in saving Earth?
But this vast distance did not mean that isolation could endure forever. Instruments within the ship intercepted radio broadcasts and, within the hour, early TV signals. The history of the planet was tabulated as facts became available. "It's not what they've done," said Bal, the second alien. A meteor shower could pass over and their clumsy instruments could interpret it as an all-out enemy attack." They went much closer to Earth, not intending to commit themselves. For a day they circled the planet, avoiding radar detection, which for them was not difficult, testing, and sampling. "What's worse is that I now find they also have missiles, range one thousand miles and upward. We can't help them," said Ethaniel.
 The humans did come to a formal agreement before the aliens left them.
 The humans did come to a formal agreement before the aliens left them.  The humans realized they were not alone in the universe. They dropped all their petty differences to defend themselves against an alien invasion.  The humans painted many pictures of the aliens to commemorate the historic event of first contact, a sign they will hold to the agreement made.  The humans were kneeling before the aliens in deference, a sign that they will hold to the agreement made.