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Neptune was the last of the Jovian planets. Pluto is a dwarf planet on the edge of our Solar System. Pluto's orbit is on the average 39.4 a.u. from the Sun. Because of this great distance, we know very little about Pluto, which was discovered only in 1930 by Clyde Tombaugh.
Pluto is much smaller than the Jovian planets and only slightly larger than Mercury. It is almost like a terrestrial planet, defiantly living in neighborhood populated by Jovian giants. Being neither Jovian nor terrestrial, Pluto is know as the enigmatic planet.
In some books, you may read that Pluto may only be seen through one of the world's giant telescopes. Fortunately, that is not entirely accurate. All the distances between the planets' orbits and the Sun are average distance. The measure of deviation from a perfect circle by a planet's orbit is known as its eccentricity and Pluto is by far the most eccentric planet in the Solar System. There is a large difference between is minimum and maximum distance from the Sun. This difference is so great that Pluto crossed over Neptune’s orbit in 1969 and was temporarily the eigth planet. It may still be possible to see Pluto through a large amateur telescope. Pluto takes almost two-and-a-half centuries to complete one revolution.
Ventia Burney of Oxford, England suggested the name Pluto, almost immediately after its discovery. Miss Burney was 11 years old at the time and suggested the name to her grandfather over breakfast one morning.