Defined as group of planets or celestial bodies that revolve around a sun such as Venus, Earth, Mars , Saturn etc. From researches, it is well known that earth supports life with not question while others such as mars, Pluto are under sturdy to see whether they can support lives. for people who live under the earth you do not even recognize where the planets are located i.e. are they below the earth where we live or in space. where do you think they are?