Explain how planetary orbits exemplifies the scientist method and the use of models.

Johannes Kepler was the one who elucidated the 3 laws of planetary orbits, the chief one being the elliptical orbits of the planets around the sun with the sun at a focal point at one end of the orbits. This was derived especially from careful observations by Tycho Brahe of the heavens  and based on his model of the orbits so was scientifically based. 

That would be a working theory.