Last updated on April 17, 2014 at 17:30 EDT

Planemos Reference Libraries

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2004-10-19 04:45:41

Planet Pluto -- Pluto is the ninth and smallest planet of our solar system. It was discovered by the astronomer Clyde Tombaugh at the Lowell Observatory in Arizona on February 18, 1930 (although the body was first photographed on March 19, 1915). Tombaugh was searching for a "Planet X" to explain the orbit of Neptune; further analysis, with seven decades more data about Neptune's position,...

2004-10-19 04:45:41

Uranus -- Uranus is the seventh planet from the sun. It is a gas giant. Physical characteristics Uranus is composed primarily of rock and various ices, with only about 15% hydrogen and a little helium (in contrast to Jupiter and Saturn which are mostly hydrogen). Uranus (and Neptune) are in many ways similar to the cores of Jupiter and Saturn minus the massive liquid metallic hydrogen...

2004-10-19 04:45:40

Jupiter -- in astronomy, fifth planet from the sun and largest planet of the solar system. Astronomical and Physical Characteristics Jupiter's orbit lies beyond the asteroid belt at a mean distance of 483.6 million mi (778.3 million km) from the sun; its period of revolution is 11.86 years. In order from the sun it is the first of the Jovian planetsJupiter, Saturn, Uranus, and...