Uranus is a member of the class of planets called the gas giants. It is the seventh planet from the Sun and the third largest planet in the solar system. Mistaken for a comet, William Herschel discovered it in 1871 before realizing it was the seventh planet. Being the first planet to actually be discovered, no one knew what to name it. Finally it was proposed to name it after the father of Saturn, "Uranus".
Uranus follows Saturn as the seventh planet from the Sun. It has an average elliptical orbit of 1,740 million miles (2,800 million km). The average distance Uranus is from Earth is 1,690 million miles (2,720 million km), At this distance, it takes light from Uranus 2 hours 45 minutes to reach Earth. From Earth, Uranus looks like a dim, greenish disk with no detailed markings. Uranus appears bluish-green because of the methane in its atmosphere that absorbs red light.
One ironic and unique figure about Uranus is that it rotates on its
side. Its axis of rotation is at an angle of 98°.
This means that Uranus, instead of spinning in an upright position like
the other planets, it rotates on its side.
The diameter across the equator of Uranus is 32,000 miles (52,000 km). It rotates once every 17 hours 14 minutes. It takes Uranus 84 years to complete on revolution around the Sun. Because it rotates on its side, Uranus has some unusual weather. For half of its revolution, one pole receives some degree of sunlight while the other pole receives none, and is in total darkness. Equatorial regions on Uranus receive two winters and two summers each year on Uranus.
On Uranus, the magnetic axis is at an angle of 60° to the spin axis. This causes the magnetic axis to miss the center of the planet by 5,000 miles (8,000 km).
The density of Uranus is 1.23 times that
of water. The mass of Uranus is 14.6 times
that of Earth. The planet is covered in a planet covering "ocean" of hot
water 5,000 miles (8,000 km) deep. Beneath
this "ocean" is a dense core about the size of Earth composed of rock and
ice. The strong magnetic field is generated within its liquid mantle. Above
the liquid ocean, whit clouds roam the blue atmosphere.
Beyond the planet, there are a series of rings made of the darkest known materials in the solar system.
The thick atmosphere of Uranus contains about 84
percent hydrogen, 14 percent helium,
2 percent methane, and little acetylene. The
atmosphere is about 6,200 miles (10,000 km)
above the surface. The clouds that form at the level in the atmosphere
that is 1.3 Earth atmosphere, methane crystals
Uranus has 15 known moons. The largest are Titania and Oberon. Both discovered by Herschel in 1787. In 1851, two more moon were discovered: Umbriel and Ariel, by William Lassell. Gerard Kuiper discovered the fifth moon, Miranda, in 1948. Its seems show although it fits together. The moons orbit the planet in this order: Miranda, Ariel, Umbriel, Titania, and Oberon.
The innermost moon of Uranus orbits the planet at a distance of 80,400 miles (129,400 km), every 1.4 days. The moon is dark and icy. The diameter is 300 miles (480 km) and its density is 1.3 times that of water. Miranda is unique because its surface looks as if it was a jigsaw puzzle that had been assembled in a hurry. Miranda looks as like it has dramatic geological activity. The surface has some impact craters.
The second innermost moon from Uranus orbits at a distance of 118,700 miles (191,000 km). It has a diameter of 720 miles (1,160 km), and completes one orbit of the planet every 2.5 days. Ariel has evidence of many impact craters and geological activity.
The next moon out orbits the planet at a distance of 165,000 miles (266,000 km), and completes one orbit every 4.14 days. This dark and ancient moon has a diameter of 740 miles (1,190 km). Ariel has a density 1.6 times that of water. The surface of Umbriel reflects only 16 percent of what sunlight reaches it, is heavily cratered. The moon's darkness may be caused by a dark dust layer covering the surface.
The largest moon of Uranus, it orbits the planet once every 8.71 days at a distance of 270,900 miles (435,900 km). Its diameter is 998 miles (1,590 km). Like Ariel, its density is 1.6 times that of water. The moon is covered in craters. The planet has a high proportion of rock. The surface has distinctive valleys and cracks as well as old, eroded craters.
The outermost large moon of Uranus, has a diameter of 960 miles ( 1,550 km), and orbits the planet once every 13.5 Earth days at a distance of 362,500 miles (583,300 km). A distinction of Oberon is that its impact craters are surrounded by clean ice that has been splashed out of its interior. There may have once been volcanic activity.
There are ten moonlets of Uranus all of which are small and dark and orbit the planet between Miranda and the outermost ring.
|Puck||105 miles (170 km)|
|Belinda||30 miles (50 km)|
|Rosalind||30 miles (50 km)|
|Portia||55 miles (90 km)|
|Juliet||45 miles ( 70 km)|
|Desdemona||30 miles (50 km)|
|Cressida||45 miles (70 km)|
|Bianca||30 miles (50 km)|
|Ophelia||12 1/2 miles (20 km)|
|Cordelia||9 1/3 miles (15km)|
The rings of Uranus are characterized by their darkness and carbonaceous
material makeup. The width is about 1 mile
(1.6 km) to 55 miles
(90 km). The ring stay in position around the planets equator in
a band between 26,000 miles (41,850 km) and
31,800 miles (51, 160 km) from the planet.
There are nine rings each made up of particles mostly 3
feet (1 meter) across. The outermost ring (the largest) is called
the Epsilon ring.
Average distance from the Sun. . . . . . . . . 1,740,000,000 miles (2,800,000,000 km)
Average temperature . . . . . . . . . . . . . . . -220°F (-140°C)
Diameter . . . . . . . . . . . . . . . . . . . . . . . 32,000 miles (52,000 km)
Atmosphere Composition . . . . . . . . . . . . Hydrogen, Helium
Number of Moons . . . . . . . . . . . . . . . . 15 known
Length of Day . . . . . . . . . . . . . . . . . . . 17 1/4 hours
Length of Year. . . . . . . . . . . . . . . . . . . 84 Earth years
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