mercury is a kind of planet & mercury is located in the solar system ->  mercury is a planet in the solar system  mercury is a planet in the solar system & planets in the solar system orbit the sun ->  mercury is a planet orbits the sun in the solar system  mercury is a planet orbits the sun in the solar system & a complete revolution / orbit of a planet around its star takes 1 / one planetary year ->  a complete orbit of mercury around the sun takes one mercury year  a complete orbit of mercury around the sun takes one mercury year & one mercury year is about 88 earth days -> a complete orbit of mercury around the sun takes around 88 earth days