1901 — the year the nuclear atom was “invented”!

[The] planetary model is an important one historically, and was accurate enough in its time (and still today) to forgive its faults. It arose naturally in the early 1900s, in a period of great confusion and uncertainty about atomic structure. With tantalizing and rather bewildering experimental hints, scientists speculated wildly about the nature of the atom. The strongest contender was the “plum pudding” model of J.J. Thomson, in which atoms were visualized to be a “pudding” of positively-charged fluid within which were embedded negatively-charged electron “plums”. In Thomson’s original paper, these plums were arranged equidistantly around a circle within the pudding and orbiting within it