In the seventeenth century, astronomer johannes kepler observed the planets revolving around our sun and analyzed data about them. he found that as the distance from the sun increases, the amount of time it takes for the planet to go all the way around the sun increases. even though kepler did not know why his observation was true, it has been found that planets in all solar systems always revolve around suns the same way. which best describes why kepler’s observation of planetary motion is a law instead of a theory? it does not discuss independent and dependent variables that can be observed or tested. it does not provide an explanation for why the relationship exists between distance and orbit time. a lot of new technology has been developed that can record more accurate data about planetary motion. a lot of different understandings of why planets move have been developed, and kepler’s provides the best explanation.