Perihelions

An object that has a perfectly circular orbit never varies in distance from the object it's going around. With the possible exception of a few spacecraft, none of the objects known to be orbiting the sun has such an orbit. Rather, the planets orbit in ellipses, however slight. So there is a point in each orbit when the planet is closest to the sun. That point is called the perihelion. Likewise, there is a point when each planet is farthest from the sun. That point is the aphelion.

Of course, the longer the orbit the longer the time between these points in the planet's orbit. Mercury goes through perihelion every 88 days. Neptune takes 165 years!

There's a separate page listing aphelion times, but here's a list of perihelion times in Universal Time for the years 2010 through 2029. The distances from the sun in astronomical units, kilometers, and miles are listed. An astronomical unit is the average distance between Earth and the sun.