Because Pluto has an orbit around the Sun which is very elliptical, there are times when it crosses Neptune's orbit and becomes closer to the Sun than Neptune. For 20 years, from 1979 to 1999, Neptune was actually farther from the sun than Pluto. For now, Pluto is back to being farther from the sun. It will be more than 230 years before Neptune and Pluto trade places again. Pluto slips inside of Neptune's orbit once every 248 Earth years for a period of twenty years.