Snipfact:

  Neptune is the furthest body from the Sun. Surface winds are the strongest of any planet at up to 2,000 km/h. Neptune’s year is so long that it has not comlpleted an orbit round the Sun since its discovery and will not until 2011. Diameter: 49,522 km Mass: 1,024,700,000,000,000 tonnes Average distance from Sun: 4,498,252,900 km Rotation: 16 hours 7minutes Orbit: 164 years 298 days Average temperature: -200.15 ◦ C Moons: 13

      All the satellites of   Uranus are called after characters from either William Shakespeare’s plays or Alexander Pope’s poem The rape of the Lock . Uranus has rings like those of Saturn, but they are visible only with a powerful telescope. Diameter: 51,118 km Mass: 868,320,000,000,000 tonnes Average distance from Sun: 2,870,972,200 km Rotation:17 hours 17minutes Orbit: 84 years 4 days Average temperature -197.15 ◦ C Moons: 27

          Saturn and its rings are being examined by NASA/European Space Agency’s Cassini probe, which reached it in 2004. In 2005 it released the Huygens probe to land on the surface ot Titan and has continued to send back data from its flybys of titan and other moon of Saturn. Diameter: 120,536 km Mass: 5,684,600,000,000 tonnes Average distance from Sun: 1,426,725,400   km Rotation: 10 hours 34   minutes Orbit: 29 years 168 days Average temperature: -139.5 ◦ C Moons: 56

        Jupiter is the largest planet in the solar system and is big enough to contain more than a thousand Earths. Four of its many moons were among the first ever astronomical discoveries made with a telescope, by Galileo in 1610. More were identified be later astronomers and in 1979 by the space probe Voyager 2. The NASA Juno mission to jupiter is planned for launch in 2011. Diameter: 142,984 km Mass: 18,986,000,000,000,000 tonnes Average distance from Sun: 778,412,010 km Rotation: 9 hours 50 minutes Orbit: 11 years 314 days Average temperature: -150 ◦ C Moons: 63

      Several space probes have flown past or landed on Mars, providing information on its atmosphere and features, such as the volcano Olympus Mons. This stands 27 km high –more than three times the height of Mount Everest. The latest craft to visit the red planet is Mars Reconnaissance Orbiter, which began a four-year orbit in 2006. NASA’s Phoenix Mars landed in May 2008. Diameter: 6,794 km Mass: 6,421,900,000,000 tonnes Average distance from Sun: 227,940,000   km Rotation: 1.025957 days Orbit: 686.98 days Average temperature: -63 ◦ C Moons: 2

   Earth is a watery planet –70 per cent of its surface appears blue –and the only one that can support life. From space, astronauts have observed cities, forest fires, roads, airports, dams and other large structures, such as the Great Pyramid and the Great Wall of china. Diameter: 12,756.3km Mass: 59,720,000,000,000 tonnes Average distance from Sun: 149,600,000 km Rotation: 0.99727 days Orbit: 365.256 days Average temperature: +15 ◦ C Moons: 1

  In size, mass, density and volume Venus is the planet most similar to Earth. Venus rotates backwards, from east to west, so the Sun would appear to rise in the east and set in the west. In April 2006 the European Space Agency’s Venus Express spacecraft reached Venus. Japan’s Venus Climate Orbiter PLANET-C will be lauched in 2010. Diameter: 12,103.6km Mass: 48,690,000,000,000 tonnes Average distance from Sun: 108,208,930 km Rotation: 243.0187 days Orbit: 224.7001  days Average temperature: +456.85 ◦ C Moons: 0

  Mercury was named after the speedy messenger of the gods because it seemed to move more quickly than the other known planets. In 2004 NASA launched its MESSENGER probe, which is due to reach Mercury in 2011. Diameter: 4,880 km Mass: 3,302,000,000,000 tonnes Average distance from Sun: 57,909,175  km Rotation: 58,6462 days Orbit: 87.869 days Average temperature: +166.86   ◦ C Moons: 0

    The Solar System was formed about 4,560 million years ago. It is made up of the eight planets –Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune –as well as their moons, comets and other bodies. These all orbit our Sun, to which they are attracted by gravity.