Outer planet
Four giganectic planets dominate the outer solar system.very different from rocky,inner planets,these strange worlds are huge are globes of gas and liquids,with no solid surface and hundreds of moons.
After the sun first formed, its heat drove gases out of the inner solar system ,leaving behind heavier compounds such as rock and metal. The rock and metal formed the solid inner planets, while the gases formed the outer planets, outer, astronomers call the outer planets gas giants, though they have solid cores. These four worlds have much in common. all have numerous
and a set of rings made of flecks of rock or ice.
Lord of the ring:
The second-largest planet and the sixth farthest from the sun,Saturn shines like a bright yellow star. Even a small telescope will reveal its most famous feature :a magnificent ring system.deposit Saturn’s size,it is only half as dense as Jupiter’s but fierce storms blow up every 30 years or so,creating giant white sports.
Saturn’s largest moon,Titan,has a dense atmos-phere and a rocky surface with seas of liquid methane.the cassini spacecraft has been orbiting Saturn since.2004 it released a probe,huygens.
Saturn profile:
Diameter…..120,536km(74,896miles)
Average surface
Temperature …….-180 C(-292F)
One spin on axis …...10.7hours
One orbit of sun….29.5earth years
Number of moons……62
Rings system:
Saturn’s miles rings are 3600km (220,000 miles) wide,they are only 10 m (30ft)thick.A scale model of the rings made with a sheet of the paper be3m(2miles)wide.beyond the main rings are hazy outer ring.photographed by cassini while the sun was behind Saturn (below).
Tospy –turvy world :
Uranus,the seventh planets from the sun,was unknown to ancient astronomers,even though it is just visible with the naked eye in perfectly clear and dark skies.it was discovered by skies.it was discovered by musician William Herschel from his back garden in Bath,England in1781.
Uranus is similar to Neptune but has a pelar blue,almost featureless face .it is the coldest of all the planets and generates very little heat from within.it orbit on its side-perhaps because it was ‘knocked over by a collision with another planets early in its history .its extreme tilt gives it very long seasons.
Uranus has a faint set of rings,which were discovered in 1977.The planet’s moons are all named after characters in works by William Shakespeare or the English poet Alexander pope.
Uranus profile:
Diameter……..51,118km(36,763miles)
Average surface
Temperature…….-193C(-315F)
One spin on axis …………17.2hours
One orbit of sun..84 earth years
Number of moons..27
Iceg iant:
Uranus pale blue colour is due to the methane in its atmosphere.water and ammonia have also been detected in these clouds.the planets contains less hydrogen and helium than Jupiter and saturn but has more rock and water.
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