The lost world: Pluto and Haron.

Pluto Diameter 2290 km Mass 1,3*10^22 kg Density 2100 kg/m^3 The period of rotation 6,38 days The average distance from the Sun 39,53 Ю.u. The period of revolution 247,7 years Excentricity of the orbit 0,249 The orbit’s slope 17,3°

Pluto is the ninth from the Sun big planet of the solar system.

It was discovered by P. Lovell. In 1915 he published his work "The treatise about the transneptune planet", where he informed about the searching of the X-planet. After Lovell's death his work was continued. The careful processing of the snapshots with the images of the star sky parts, where the new planet was thought to be found was not successful at that time (later on when Pluto had been discovered the snapshots of 1991 were processed again and there were the four very weak and invisible earlier imeges of the planet seen).

Pluto discovery was met with the enthusiasm by the astronomers though there apeear the sceptical statements. To the opinion of several investigators Pluto discovery was to some exand ocasional one, for its mass is insufficient to influence the motion of Uranus. Many problems concerning Pluto were solved only in the new step of the space science development, when the cosmic apparatus appeared.

Its mass is about 1/30 of the planet’s mass. 20000km from the centre of Pluto and rotates around it with the period of 6,4 terrestrial days, which is equal to the period of the planet’s rotation, so Pluto and Haron rotating as a single unit considered to be an integer double system.

Pluto differs from the other planet for it resembles the captured asteroid in the solar system (or two asteroids).