Is this paragraph correct grammatically?

Years ago, a star wandering blindly through space happened to come near the sun. It must have raised tides on the surface of the sun and created a disturbance. As this star would have come nearer, the tides would have been higher and ultimately developed into big mountains. As the second star began to move away its tidal pull had become so powerful that this mountain was torn to pieces and threw off small parts of itself into the space.

Can we use below mentioned sentence in place of this sentence?

As this star had come nearer, the tides would have become higher.

What will be the difference?