Pluto has not finished a single orbit around the Sun since humans discovered it in 1930.

Clyde Tombaugh discovered Pluto on February 18, 1930, at the Lowell Observatory in Arizona. Pluto is about 3.67 billion miles away from the Sun on average. This is roughly 39 times farther than Earth's distance from the Sun.Objects farther from the Sun travel slower because gravity is weaker at great distances. Pluto moves at about 2.9 miles per second. Earth moves much faster at about 18.5 miles per second.Pluto's path is shaped like a stretched-out oval rather than a circle. This path is so long that Pluto will not return to its 1930 starting position until March 23, 2178. By then, Earth will have completed 248 full orbits.During this single Pluto year, Earth will have gone through 248 sets of seasons. Scientists use these measurements to understand how gravity works across our solar system. Pluto remains the slowest-moving major object in our local space neighborhood.