(Classical mythology) The god of the underworld in ancient mythology; brother of Zeus and husband of Persephone; Also called: Hades, Aides, Aidoneus.
In Greek mythology, the lord of the underworld (Roman Dis), sometimes known as Hades. He was the brother of Zeus and Poseidon.

The second smallest planet and the farthest known from the sun; has the most elliptical orbit of all the planets.
In astronomy, the smallest and, usually, outermost planet of the Solar System. The existence of Pluto was predicted by calculation by Percival Lowell and the planet was located by Clyde Tombaugh in 1930. Its highly elliptical orbit occasionally takes it within the orbit of Neptune, as in 1979–99. Pluto has a mass about 0.002 of that of Earth.
mean distance from the Sun 5.8 billion km/3.6 billion mi
equatorial diameter 2,300 km/1,400 mi
rotation period 6.39 Earth days
year 248.5 Earth years
atmosphere thin atmosphere with small amounts of methane gas.
surface low density, composed of rock and ice, primarily frozen methane.
satellites one moon, Charon.
Charon, Pluto's moon, was discovered 1978, revolving around Pluto with the same period as Pluto's rotation, remaining over the same point on Pluto's surface and showing the same face. It is composed mainly of ice and it is possible the pair may be a double planet system.