Uranus is the seventh planet from the Sun and is the third largest in the solar system. It was discovered by William Herschel in 1781. It has an equatorial diameter of 51,800 kilometers (32,190 miles) and orbits the Sun once every 84.01 Earth years. It has a mean distance from the Sun of 2.87 billion kilometers (1.78 billion miles). The length of a day on Uranus is 17 hours 14 minutes. Uranus has at least 22 moons. The two largest moons, Titania and Oberon, were discovered by William Herschel in 1787.
The atmosphere of Uranus is composed of 83% hydrogen, 15% helium, 2% methane and small amounts of acetylene and other hydrocarbons. Methane in the upper atmosphere absorbs red light, giving Uranus its blue-green color. The atmosphere is arranged into clouds running at constant latitudes, similar to the orientation of the more vivid latitudinal bands seen on Jupiter and Saturn. Winds at mid-latitudes on Uranus blow in the direction of the planet's rotation. These winds blow at velocities of 40 to 160 meters per second (90 to 360 miles per hour). Radio science experiments found winds of about 100 meters per second blowing in the opposite direction at the equator.
Uranus is distinguished by the fact that it is tipped on its side. Its unusual position is thought to be the result of a collision with a planet-sized body early in the solar system's history. Voyager 2 found that one of the most striking influences of this sideways position is its effect on the tail of the magnetic field, which is itself tilted 60 degrees from the planet's axis of rotation. The magnetotail was shown to be twisted by the planet's rotation into a long corkscrew shape behind the planet. The magnetic field source is unknown; the electrically conductive, super-pressurized ocean of water and ammonia once thought to lie between the core and the atmosphere now appears to be nonexistent. The magnetic fields of Earth and other planets are believed to arise from electrical currents produced in their molten cores.
In 1977, the first nine rings of Uranus were discovered. During the Voyager encounters, these rings were photographed and measured, as were two other new rings and ringlets. Uranus' rings are distinctly different from those at Jupiter and Saturn. The outermost epsilon ring is composed mostly of ice boulders several feet across. A very tenuous distribution of fine dust also seems to be spread throughout the ring system.
There may be a large number of narrow rings, or possibly incomplete rings or ring arcs, as small as 50 meters (160 feet) in width. The individual ring particles were found to be of low reflectivity. At least one ring, the epsilon, was found to be gray in color. The moons Cordelia and Ophelia act as shepherd satellites for the epsilon ring.
The greenish color of it atmosphere is due to methane and This view of Uranus was acquired by Voyager 2 on January 10, 1986. The blue-green appearance of its atmosphere results from methane and high-altitude photochemical smog. This gas absorbs red wavelengths from the incoming sunlight, leaving the predominant bluish color seen here.
Our knowledge of the internal structure of Uranus is inferred from the planet's radius, mass, period of rotation, the shape of its gravitational field and the behavior of hydrogen, helium, and water at high pressure. Its internal structure is similar to that of Neptune except for the fact that it is less active in terms of atmospheric dynamics and interior heat flow. Uranus is composed of an outer envelope of molecular hydrogen, helium and methane roughly the mass of one to two Earths. Below this region Uranus appears to be composed of a mantle rich in water, methane, ammonia, and other elements. These elements are under high temperatures and pressures deep within the planet. The mantle is equivalent to 10 to 15 earth masses. Uranus's core is composed of rock and ice, and is likely no more than one Earth mass.
The plain aquamarine face of Uranus confirms the fact that Uranus is covered with clouds. The sameness of the planet's appearance shows that the planet's atmosphere is mostly composed of one thing, methane. The planet appears to be blue-green because the methane gas of the atmosphere traps red light and does not allow that color to escape. Beside clouds of methane crystals low in the atmosphere, smog, composed of ethane (the same product that can provide fuel for automobiles), is also present high in the atmosphere. The cloud particles constantly recycle themselves, first creating then destroying the heaviest crystals. This is an indication that Uranus' atmosphere is still evolving from its formation out of the solar nebula. Because Uranus lies on its side, Uranus has very strange seasons. Motions in the cloud patterns indicate that, like Jupiter and Saturn, the basic weather of Uranus can be described as a striped pattern of winds. This means that, even though the pattern is hard to see, Uranus is striped, just like Jupiter and Saturn.
The magnetosphere of Uranus is medium sized, but still much bigger than the Earth's. It holds all of Uranus' moons. It is probably made in the middle of the planet, and with ice, rather than with iron at the core. The magnetosphere of Uranus has a very strange tilt. The extreme tilt, combined with the extreme tilt of Uranus itself, makes for a completely strange magnetosphere, one which has twisting structure! Mathematical theory suggests that the rings of Uranus sweep the particles in the magnetosphere into the atmosphere! The Aurora on Uranus is difficult to detect, and so are radio signals from Uranus, which means that the magnetosphere of Uranus may be almost empty!
Uranus has 27 fascinating moons and a complicated ring system. The ring is a completely different form of ring than the one around Saturn or Jupiter. At Uranus there is a very obvious partial ring, or "ring arc". Many moons are icy moons with fascinating surface features. These icy moons have no atmosphere nor magnetosphere. The interiors of these moons are not active, and there is not much possibility for life. The moons are, in order; Cordelia, Ophelia, Bianca, Cressida, Desdemona, Juliet, Portia, Rosalind, Belinda, and Puck. These moons are part of a group called the "Small Moons". Icy moons of Uranus are; Miranda, Ariel, Umbriel, Titania, Oberon, Caliban, and Sycorax. In 1999, four more Uranian moons were found. They include Prospero, Setebos, Stephano and 1986 U 10.
Astronomers have discovered new moons orbiting the planets Uranus and Neptune. Counting the new moons, Uranus now has 27 moons that we know about. Neptune has 13 that have been found so far. All of the newfound moons are small, having diameters less than 100 km (60 miles). Mark Showalter of Stanford University and NASA's Ames Research Center and Jack Lissauer of Ames discovered two new moons of Uranus. Those moons have been given temporary names: S/2003 U1 and S/2003 U2. The moons were found in pictures taken by the Hubble Space Telescope. Uranus has five large moons named Ariel, Miranda, Oberon, Titania and Umbriel. S/2003 U1 and S/2003 U2 are closer to Uranus than all of the large moons. Scott Sheppard and David Jewitt discovered two more moons of Uranus. Those moons are called S/2003 U3 and S/2001 U2 for now. Sheppard and Jewitt used a telescope on top of a volcano in Hawaii to find these moons. S/2001 U2 has a big orbit and takes almost 8 years to go around Uranus! Astronomers also found two new moons orbiting Neptune. Matthew Holman and B. Gladman discovered S/2002 N4. Jewitt, Sheppard and Jan Kleyna discovered S/2003 N1. These moons orbit very far from Neptune. They are farther away from their "home" planet than any other moon that has been found so far. They take about 25 years to go around Neptune once! Some of the moons had been seen before in the last few years. To figure out the orbit of a moon, astronomers need to see it a few times to know how it moves. They don't count a moon as "discovered" until they are sure that it orbits a plane.
Uranus has puzzled scientists ever since the probe Voyager 2 did a flyby in 1986 and found that its magnetic field appeared to break the planetary rulebook. The evidence from Earth, Jupiter and Saturn determined that a planet's magnetic field should be like that of a bar magnet, with a north and south pole that runs roughly along the sphere's rotational axis. But Uranus -- and Neptune, too, Voyager found -- is radically different. Their magnetic fields are tipped over (the north-to-south line lies midway to the equator or even closer) and there are two north and two south poles, as if the field were produced by two bar magnets. The reason for this, according to a new theory published on Thursday in the British journal Nature: The underlying structures of Uranus and Neptune are radically different from what was previously assumed about these cold, distant planets. In the case of Earth, for instance, the planet's solid inner core is bathed in a molten iron-rich fluid, which is propelled around by the planet's rotation and by convection currents, which transfer heat from the core toward the surface. And in Jupiter and Saturn, which are "gas giants" rather than rocky planets like Earth, the magnetic field is believed to derive from a thick layer of sub-surface hydrogen, compressed by gigantic pressures into an electric soup of protons and electrons, which revolves around a small solid core. Where Neptune and Uranus differ, the new study says, is that even though they are gas giants, their interior structure is different from those of Jupiter and Saturn. It suggests that these two outer planets may have only a thin layer of metallic convecting fluid. This has a big effect on the magnetic field, limiting it to a thin "shell" just under the gassy hydrogen surface. That phenomenon may also cause the field to be tipped on its side compared to the rotational axis and also inflict the "quadrupole" effect. The study's co-authors are Jeremy Bloxham and Sabine Stanley of Harvard University, whose computer model of the planets' interior strongly replicates the strange magnetic fields detected by Voyager 2. Hard evidence to back it will only come from a probe to Uranus or Neptune, they admit. No such mission is being planned for the moment, but scheduled treks by US and US-European probes to Saturn and Mercury should yield exciting new data to test the theory of how planetary magnetic fields are born, they say.
In essence I choose Uranus because it is my favorite planet in our solar system. I have always been fascinated by this wonderful enigma known as Uranus. I look forward to future knowledge in regards to this mythical planet. Learning about this planet was both an honor and a privilege for me.
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