The Star Garden
HTML Comment Box is loading comments...
Miranda
NASA's Voyager 2 reached Uranus in 1986 and discovered ten new moons. Uranus is similar to Jupiter and Saturn, with an atmosphere primarily composed of hydrogen and helium, but it also contains trace amounts of hydrocarbons and a large amount of frozen water, ammonia and methane. Uranus has the coldest planetary atmosphere in the Solar System and can reach over minus two hundred degrees Celsius. The core is composed of ice and rock. Uranus has a magnetosphere but the whole planet is tilted on its side so that its magnetic poles are at the equator.
Uranus has a ring system similar to Saturn's, except that it did not form when the planet did and orbits at an angle of nearly ninety degrees. It has almost thirty other satellites, the five largest are Miranda, Ariel, Umbriel, Titania and Oberon. The largest of these is Titania which is about half the diameter of the Moon. Uranus' moons are mostly composed of frozen water, ammonia and carbon dioxide as well as silicate rock.
Miranda Ariel Umbriel Titania Oberon (to scale)
Neptune
Neptune is the furthest planet from the Sun, orbiting at about thirty AU (one AU is the distance between the Earth and the Sun). It was discovered almost seventy years after Uranus. Neptune is the third most massive planet in the Solar System after Jupiter and Saturn, it is the fourth largest planet, having a slightly smaller diameter than Uranus. It takes over sixty thousand Earth days for Neptune to orbit the Sun, this is over on hundred and fifty Earth years. One day on Neptune is just over sixteen hours long. Neptune was not visible from Earth before the invention of the telescope. Like Mercury, Venus, Mars, Jupiter and Saturn, but unlike Uranus, Neptune is named after a Roman God, the god of the sea.
NASA's Voyager 2 probe reached Neptune in 1989 before leaving on a trajectory which will take it out of the Solar System. Neptune's atmosphere is similar to Uranus', composed mostly of hydrogen and helium with trace amounts of hydrocarbons and frozen ammonia and methane. Neptune's core is mostly composed of ice and rock.
Neptune and Triton
Neptune has a faint ring system and thirteen known moons, the largest of these is Triton which contains over ninety percent of the mass of all the Neptunian moons and is the only one which is spherical. Triton is the only moon in the Solar System to have a retrograde orbit, this mean it orbits in the opposite direction to Neptune's rotation. It is thought to have once been a dwarf planet like Pluto, but was captured by Neptune's gravitational pull.
Triton is composed of a core of rock and metal with an icy mantle and a crust of active volcanoes and frozen nitrogen, up to thirty five percent of its mass is composed of frozen water. Triton has a thin nitrogen atmosphere, it is the coldest atmosphere in the Solar System, at over minus two hundred degrees Celsius.
References
Uranus and Neptune
Uranus
Uranus is the seventh closest planet to the Sun and unlike the first six planets, it was not discovered until the invention of the telescope, although it is just visible with the naked eye. Uranus is the third largest planet in the Solar System, after Jupiter and Saturn, it is larger than Neptune but less massive. It takes over thirty thousand Earth days for Uranus to orbit the Sun, this is over eighty Earth years. One day on Uranus is just over seventeen hours long.
Unlike Mercury, Venus, Mars, Jupiter and Saturn, Uranus was not named after a Roman God. It is instead named after the Ancient Greek god of the sky, the father of the Greek God Kronos, which corresponds to the Roman God Saturn, and the grandfather of Zeus, known to the Roman's as Jupiter.