A student is talking to her teacher.
S : I hear that scientists are planning to study asteroids and meteors, right?
T : Yes. They want to determine whether Earth is in danger of being struck by such a rock.
S : What if they discover that a big one is coming straight for us?
T : In that case, there are two things they can do. They can launch rockets to push the rock off its course.
S : So that it will miss Earth, right?
T : Right. And if that fails, we can try destroying the rock with nuclear missiles.
S : Wow! I never thought that nuclear weapons could save the world instead of ending it!