Whose theory explained the structure of the atom as a planetary model?

Ernest Rutherford, the New Zealand–born physicist, proposed the nuclear or planetary model of the atom in 1911. His interpretation of the gold foil experiment showed that most of the atom is empty space, with nearly all its mass concentrated in a small central nucleus. This was a major break from earlier “plum pudding” models of the atom. Rutherford later won the 1908 Nobel Prize in Chemistry for his work on radioactivity, not for the atomic model itself.