Neptune has the longest period of revolution around the sun at 165 Earth years. In contrast, Earth's period of revolution is 365.2 days, the time measured as one year.
Uranus is second in line, taking 84 years to accomplish the turn. The planet with the shortest period of revolution is Mercury, which takes only 88 days to revolve around the sun.
Until 2006, Pluto was the planet with the longest period of revolution around the sun, taking 248 years to complete a full revolution. However, scientists now consider Pluto to be a dwarf planet. Pluto has an elliptical orbit around the sun, so it sometimes gets closer to the sun than Neptune.