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NEBULAE
GLOSSARY
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Uranus:The Tilted
Planet
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Name of
the Planet |
Uranus |
Position
in Solar System |
The seventh
planet is named after the Greek sky god. Seventh Planet in the
Solar System. |
Constituents |
ice, hydrogen,
helium |
Atmosphere |
hydrogen,
helium |
Average
Distance from Sun |
2,870,000,000
km/1,783,000,000 mi |
Orbit
Time |
84 Earth
years |
Diameter |
50,800
km/31,560 mi |
Average
Density (water=1) |
1.3 |
Satellites |
Ariel,
Belinda, Bianca, Cordelia, Cressida, Desdemona, Juliet, Miranda,
Oberon, Ophelia, Portia, Puck, Rosalind, Titania, Umbriel |
Average
Surface Temp |
218ºC
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Rotational
Period |
17.9 hours |
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Description:
Lying deep in the void, Uranus
is practically invisible to the naked eye. Even through the telescopes.
It is difficult to study this planet in great detail. Only recently,
the spacecraft Voyager 2 unveiled many of the secrets of Uranus.
On January 24, 1986 at 1800 GMT, Voyager locked in on Uranus and
was there for about 6 hours. Voyager has taught the scientists more
about Uranus that they had learnt in the entire 205 years since
its discovery by the then amateur astronomer Sir William Herschel
in 1781.
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Uranus is so far from the Sun - about 19 times
than that of the distance between the Earth and the Sun, that from
Uranus, the Sun appears as only a tiny disk of intense light. This
massive planet with a diameter of 15800 km is like Jupiter or Saturn.
At the center of the planet, we find a core of rock and ice, slightly
larger than the Earth with a temperature of about 7000 degrees C.
This is hotter than the surface of the Sun! The atmosphere of Uranus
is made up of hydrogen, helium and a large amount of methane which
gives it a bluish-green color. Uranus rotates on its own axis in
about 17 hours 12 mins. Like Venus, the sense of rotation is retrograde.
Uranus takes 84 years to complete one revolution around the Sun.
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![](images/Planets/Uranus/UranusAnim%5B1%5D.gif)
Image:Rotating Neptune.(Animated gif)
Source:Copzilla.com
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Unlike other planets,
its rotational axis is tilted at an angle of 98 degree to the plane
of revolution of the planet. Thus, for a long time, one pole points
almost straight at the Sun, the other pole is aimed Sunward. While
one pole is sunlit for 42 Earth years, the other pole is plunged into
night for an equally long time. This makes Uranus a most unusual planet
since it seems flopped over so that it lies almost on its side. |
![](images/Planets/Uranus/uranir.gif)
Image: Rotation of Uranus
Credits: E.Karkoschka(University of Arizona and Planetary Lab) and
NASA
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![](images/Planets/Uranus/uranus.gif)
Image: Rings of Uranus
Source: Hutchinson Encyclopedia
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The Rings of Uranus:
The rings of Uranus are made
up of particles in two distinct size ranges. Many are between centimeters
and meters across, but most are no more than few thousandths of
a millimeter across. Uranus has a ring system, discovered in March
1977, even before the arrival of Voyager 2. The discovery of Uranus'
ring was very interesting. In 1977, Uranus was to pass infront of
a faint star.This phenomenon is known as an occultation. As the
scientists aimed their telescopes to watch the occultation, the
star seemed to flicker five times, there after, Uranus covered it
when the star, reappeared, it again winked five times. Scientists
concluded that this was due to new rings around this planet.Later
researches found four more rings. Voyager 2, has discovered three
more rings around the planet. All these rings are dark, thin and
narrow. They are composed of lumps of rocks which lack an icy coating,
making them appear dark and invisible.
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Before the observations of
Voyager, only five moons of the planet were known. They are Oberon,
Umbriel, Titania, Ariel and Miranda. Voyager has discovered ten
more moons of Uranus. The photographs of Titania and Oberon showed
that the surface of both the moons were pocked. with meteoritic
impacts which had pulverized the gray surface and exposed an underlying
layer of ice. Both these moons are about 1500 km in diameter.
The recent discovery of the new rings and moons around planet Uranus
have proved right an Indian astronomer Dr.J.J.Rawal, and Director,
Nehru Planetarium, Mumbai. He had in has research papers in international
journals specified in 1981, the locations of the satellites and rings
in the region where they were spotted by Voyager 2. |
Interesting Facts:
-The Sun is 363 times as bright from the Earth
as from Uranus.
-Uranus is 14.5 times as massive as the Earth.
-If Uranus were hollow, it could contain 64 Earths.
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Historical Events
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13 March, 1781 |
Hanover-born British astronomer
Sir William Herschel discovered Uranus within the boundaries
of the constellation Gemini. |
11 January, 1787 |
Herschel discovered Titania
and Oberon. |
24 October, 1851 |
British astronomer William
Lassel discovered the moons of Uranus - Ariel and Umbriel. |
25 January,
1870 |
British astronomer W.Buffham became
the first observer to record definite markings of Uranus.
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10 March, 1977 |
James Elliot, Edward Dunham
and Doug Mink, flying aboard the Kulper Airborne Observatory
discovered the rings of Uranus. |
3 March, 1986 |
Voyager 2 scientists discovered
Portia and Rosalind. |
24 January,
1986 |
Voyager 2 flew
within 81433 km of the cloud tops of Uranus, on its way to Neptune.
Voyager 2 was launched on 20 August, 1977. |
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