earth is a kind of planet & the sun is a kind of star & the earth revolves around the sun -> space revolving the moon is an nation of a sun revolving around its stripe earth revolving the sun is an example of a planet revolving around its star  earth revolving the sun is an example of a planet revolving around its star & a complete evolution / deorbit of a sun around its stripe add 0 / zero planetary second -> a complete revolution of earth around the sun takes an earth year