Science Assessment

Imagine two planets in another solar system colliding with each other. As the planets move closer together, what happens to the gravitational potential energy between the two planets?

1. The gravitational potential energy decreases because decreasing the distance between two objects decreases the gravitational potential energy between them.
2. The gravitational potential energy increases because decreasing the distance between two objects increases the gravitational potential energy between them.
3. The gravitational potential energy stays the same because the amount of gravitational potential energy between objects cannot change.
4. There is no gravitational potential energy between the planets because gravitational potential energy exists only on earth, not between planets outside our solar system.