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The Planets .... brought to you by QuasArt Web Designs.
U
R A N U S (7th planet from the Sun)
Uranus is the ancient
Greek deity of the Heavens, the earliest supreme god.
Uranus was the son and mate of Gaia the father of Cronus (Saturn) and
of the
Cyclopes and Titans (predecessors of the Olympian gods).
CHAPTERS
I
II
III
IV
V
VI
VII
VIII
IX
X
XI
MOONS
INTRODUCTION
I


Uranus
7th planet from the Sun in the solar system, equivalent in brightness
to a sixth-magnitude star and represented by the symbols ? and ?.
It ranks seventh in order of distance from the sun, revolving outside
the orbit of Saturn and inside the orbit
of Neptune (see Solar System). Uranus
was accidentally discovered in 1781 by the British astronomer Sir
William Herschel and was originally named the Georgium Sidus (Star
of George) in honor of his royal patron King George III of Great Britain.
The planet was later, for a time, called Herschel in honor of its
discoverer. The name Uranus, which was first proposed by the German
astronomer Johann Elert Bode, was in use by the late 19th century.
Uranus has a diameter of 51,120 km (31,771 mi), and its mean distance
from the sun is 2.87 billion km (1.78 billion mi). Uranus takes 84
years for a single revolution, or orbit, and 17 hr 15 min for
a complete rotation about its axis, which is inclined 98° to the plane
of the planet's orbit around the sun.

Uranus's atmosphere consists largely of hydrogen and helium, with
a trace of methane. Through a telescope the planet appears as a small,
bluish-green disk with a faint green periphery. Compared to the earth,
Uranus has a mass 14.5 times greater, a volume 67 times greater, and
a gravity 1.17 times greater. Uranus's magnetic field, however, is
only a tenth as strong as earth's, with an axis tilted 55° from the
rotational axis. The density of Uranus is approximately 1.2. In 1977,
while recording the occultation of a star behind the planet, the American
astronomer James L. Elliot discovered the presence of five rings encircling
the equator of Uranus. Named Alpha, Beta, Gamma, Delta, and Epsilon
(starting from the innermost ring), they form a 9400-km- (5840-mi-)
wide belt extending to 51,300 km (31,860 mi) from the planet's center.
Four more rings were discovered in January 1986 during the exploratory
flight of Voyager 2 (see Voyager).
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The
planet Uranus (the bright blue object) is surrounded by its five
largest satellites clockwise from top left, Ariel, Umbriel, Oberon,
Titania, and Miranda, in this collage created from photographs
taken by the United States Voyager 2 spacecraft in 1986.
NASA |
In addition to its rings, Uranus has 17 satellites,
ten of which were discovered by Voyager 2. Fifteen of Uranus's moons
revolve about its equator and move with the planet in an east-west direction.
The two other moons, discovered in 1997, orbit Uranus from west to east
and at a large angle to the planet's equator. All of the moons are named
for characters in the works of English playwright William Shakespeare.
The two largest moons, Oberon and Titania, were discovered by Herschel
in 1787. The next two, Umbriel and Ariel, were found in 1851 by the
British astronomer William Lassell. Miranda, thought before 1986 to
be the innermost moon, was discovered in 1948 by the American astronomer
Gerard Peter Kuiper. Voyager 2 discovered ten moons-Cordelia, Ophelia,
Bianca, Cressida, Desdemona, Juliet, Portia, Rosalind, Belinda, and
Puck-when it visited the planet in 1986. Until 1997, scientists believed
that Uranus was the only gas giant planet with no irregular moons-small,
oddly-shaped bodies that orbit at angles to the planet's equator.
In 1997 a group of Canadian and American scientists using the large
Hale telescope on Mount Palomar in California found two irregular moons
orbiting the planet far out from the other moons. The proposed names
for these moons are Caliban and Sycorax.
SATELLITES
AND MOONS
III
COMING
SOON
SPACECRAFT
MISSIONS
TO URANUS
II
WEB
LINKS
IV
COMING
SOON
WEB
LINKS
XI
COMING SOON
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Uranus |
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