Pluto was first discovered in 1930, by a fortunate accident, by American Astronomer Clyde Tombaugh, and is the farthest planet in the known Solar System. Prior to its discovery, due to the erratic orbits of Uranus and Neptune it was suspected that the pull of gravity from a 9th planet, called “Planet X”, was the culprit.
The planet is named after the god of the underworld from Roman mythology; the Greek counterpart is Hades, who is also the god of the underworld. The name was probably given, because of it being furthest from the Sun and being in perpetual darkness.
Little is known of the planet, and has never been observed by telescope, nor has it been seen close-up from a spacecraft.
Pluto has an eccentric orbit. Between 1979 and 1999 the planets orbit brings it closer to the Sun the that of Neptune, so at the that moment Neptune is the farthest planet in the Solar System.
Scientists perceive that the planets atmosphere flakes into a methane “snow” and falls out of the thin atmosphere onto the surface, when the planet orbit is furthest away from the Sun. When it approaches the Sun the increasing warmth turns the methane snow into a gas, and the atmosphere is restored.
Mars has 5 moons, the largest named Charon, which was first detected in 1978, and is about half the size of Pluto. Charon is named for the mythological figure who ferried the dead across the River Acheron into Hades.
Pluto and Charon orbit each other like double planet. Each one keeps the same hemisphere facing towards each other and a at some periods during Pluto’s year Charon is eclipsed at each revolution.
The other smaller moons are named Nix and Hydra which were discovered in 2005, S/2011 discovered in 2011 and S/2012 discovered in 2012.
In 2013 scientists have suggested that Pluto may have 10 more undiscovered moons
The planet Mars is approximately 1,430 miles in diameter, and is 0.002 the size of Earths mass. It is also 2.7 billion miles from Earth. The length of a year on Venus equals 248 Earth years, and a day lasts approximately 6.9 Earth days.
Unfortunately, in 2006, after 75 years, astronomers voted in a controversial decision of demoting Pluto down to the newly created classification of “dwarf planet”.
While once known as the 9th planet it is now the largest known member in the Kuiper Belt, a shadowy disk-like area beyond the orbit of Neptune populated by more than a trillion comets.
But good news, in 2006 NASA dispatched an ambassador to the planetary frontier. The New Horizons spacecraft is approximately halfway between Earth and Pluto, its dramatic flight past the icy planet and its moons will happen in July 2015.