How has the concept of a "planet" changed since the 16th century? Do you think this shows scientific accuracy or disproves future facts, as one assumes that they will be discredited in time too?

Science keeps "improving", so the scientific theories and ideas from the past are either expanded on or proved to be false. The concept of planets has definitely seen changes, with Pluto peven being considered not a planet. In the 20 century we believed there were 9 planets but now there is considered to be 8. Science exists as it is but as humans we are constantly discovering more of it because of improvement in the times and technology. Science that proves to be accurate will never be discredited though it will be improved upon.