If I describe to you what I can do at my backyard , can you tell me what kind of fence I have?I can throw rambutan seeds out of my backyard but occasionally it land inside the house compound. You have no idea what kind of fence I have but with the description you can model one.
Rutherford did a similar expt, he kept throwing alpha particles at thin gold foil and trying to model the gold nucleus. If alpha particle passes through most of the time means there is lots of empty space(nucleus is small) . There are rare occasions when it bounces right back means the nucleus is small and massive and charged positively.
