Vivekanand Vellanki

Imagine a miniature model of our solar system - a massive ball (sun) in the centre and smaller balls (planets) rotating around the sun. The system also has huge gaps in the middle.

Now, imagine someone used a water hose to shoot water at this miniature model. When the water hits an object, the water bounces back or deflects based on where it hit.

Most of the water will go straight through because of the HUGE gaps in between. Some of the water will get deflected as it hits the planets and/or sun. Very little of the water will bounce back as it hits the sun head-on and bounces back.

This is pretty much what Geiger and Marsden found out when they did this experiment under the guidance of Rutherford. Hence, they concluded that the atomic structure was like the solar system - with most of the mass concentrated in the centre and with electrons orbiting the nucleus. They also found that most of the space was empty because most of the rays just passed through.