Physical data
Equatorial diameter: 31,693 miles
Mean cloud temperature: -315 degrees F
Mean radius: 25362 km
Uranus Equator Radius: 25,559 km
Mass: 86.83 1024 kg, 14.48 times earth's
Volume: 6,833 x 10 km3
Mean density: 1,318 kg/m3
Density: 1.28 g/cm3
Gravity 1.15 Earth=1
Gravity (eq., 1 bar): 8.69 m/s2
Escape velocity: 21.3 km/s
Bond albedo: 0.90
Visual geometric albedo: 0.51
Visual magnitude V (1,0): -7.19Orbital parameters
Orbit period: 84.01 Earth years
Rotation period: 0.72 Earth days
Average distance from sun or Semimajor axis: 2,871.0 x 106 km, 19.18
au
Sidereal orbit period: 30,685.4 days
Tropical orbit period: 30,588.740 days
Perihelion: 2,734.0 106 km
Aphelion: 3,005.2 106 km
Synodic period: 369.66 days
Mean orbital velocity: 6.82 km/s
Orbit inclination: 0.770 degrees
Orbit eccentricity: 0.04718
Sidereal rotation period: 17.24 hours
Obliquity to orbit: 97.86 degrees
Length of day: 17 hr., 14 min.
Length of year: 84 earth years
Tilt of axis: 98 degrees from vertical |
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Atmosphere
Surface Pressure: >100 bars
Average temperature: ~58 K
Temperature at 1 bar: ~76 K
Density at 1 bar: ~0.42 kg/m3
Wind speeds: 0-200 m/s
Scale height: 27.7 km
Mean molecular weight: 2.64 g/mole
Atmospheric
composition
Major: Molecular hydrogen (H2) - 82.5%; Helium (He) - 15.2%; Methane (CH4) -
~2.3%
Minor (ppm): Hydrogen
Deuteride (HD) - ~148
Aerosols: Ammonia ice, water ice, ammonia hydrosulfide, methane ice (?)
About
Uranus is the seventh planet from the Sun in our solar system.
The third largest planet, Uranus is one of the "gas giant" planets; the other
"gas giants" are Saturn, Jupiter, and Neptune. Hydrogen, helium, water, and
probably methane, ammonia, rock, and metal make up Uranus. Small amounts of
methane in the planet's upper atmosphere cause it to have a blue-green color
when viewed through a telescope.
When Sir William Herschel discovered Uranus by accident in
1781, it became the first planet discovered since the times of the Greeks and
Romans. This is interesting because Uranus is the furthest planet from Earth
that can be seen without a using a telescope, yet the ancient astronomers didn't
discover it. Uranus was originally named "Star of George" in honor of King
George III of Great Britain. The modern name of the planet comes from the Greek
god who was the first god of the sky.
Uranus' mass is about 14 times greater than the Earth's mass
and its density is about one-quarter as great as our planet's density. The
diameter at Uranus' equator is more than four times the Earth's diameter. On
March 10, 1977, astronomers discovered that Uranus had rings. It has a dark
ring-system, first detected in 1977with at least 10 dark rings, which range in width from less than 3
miles to over 60 miles (5 km to 96 km). The rings are very different from
Saturn's bright rings; they are made of unusually dark material. From November
1985 to February 1986, Voyager 2 visited Uranus. It is the only spacecraft to
have ever visited the planet.
Instead of spinning like the other planets, Uranus spins on
its side. It's almost as if the planet had been tipped over. Because of this,
one of the planet's poles faces towards the Sun, then its equator faces the Sun,
and finally its other pole faces the Sun. Therefore, day and night on Uranus are
very different than day and night on Earth. In fact, a "day" on the planet's
Polar Regions lasts 42 years and is followed by 42 years of "night." A year on
Uranus is equivalent to 84 years on Earth.
Uranus is a giant planet, but was not identified as a planet
until 1781, when it was discovered by William Herschel. There is an Earth-sized
rocky core, which seems to be overlaid by an ocean of superheated water more
than 8000 kilometers deep. It has 15 satellites, of which 10 were discovered by Voyager 1.
They are made mostly of ice and have many craters. Miranda, Ariel, Umbriel,
Titania, and Oberon are the planet's major moons.
Uranus' axial inclination of 97.86ŗ is unique in the Solar System. The equator
was present to the Sun in 1966; the North Pole in 1985. As with the other "gas
giants", the atmosphere is made up mainly of Hydrogen and Helium, with trace
amounts of Sulfur, Methane and Ammonia. The Methane is what gives it the
blue-green color.
It shines at magnitude 5.7, making it visible in binoculars and even to the
naked eye of a keen observer. The two outer moons of Uranus, Titania and Oberon,
will be ~14th magnitude; bright enough to observe in an 8-inch telescope. |
