Planets around other stars were hypothetical until they were detected using specific observational techniques that were hypothesized to collect the correct data to show their existence. The data collected about these exoplanets, plus our observations of our own set of planets, has led to the elimination of some theoretical models about how, when and where planets form, and allowed other theoretical models to advance. Early models hypothesized that other solar systems would resemble our solar system; the data collected so far suggests that few planetary systems resemble ours, and therefore the early models were incorrect. Scientists in the field are still hypothesizing and theorizing as more and more data is collected, and newer models of planetary formation have greatly changed the theory of how our solar system formed and developed. When I was young, it was accepted that the planets formed where they are today; the latest theories suggest that the planets bounced around before finally settling down in roughly their current orbits.
